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THE 

MOVEMENTS  AND  HABITS 


OF 


CLIMBING     PLANTS. 


BY    THE    SAME    AUTHOR. 


ON  THE  ORIGIN  OF  SPECIES  BY  MEANS  OF  NATURAL  SE- 
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THE  J    ^^  ^    3  6 

MOVEMENTS    AND    HABITS 


CLIMBING  PLANTS. 


By   CHAKLES    DARWIN,    M.A.,    F.E.S., 


SECOND  EDITION,  REVISED. 


WITH    ILLUSTRATIONS. 


NEW  YORK : 

D.    APPLETON    AND    COMPANY, 

549  AND  551  Broadway. 
1876. 


PREFACE. 

This  Essay  first  appeared  in  the  ninth  volume  of 
the  'Journal  of  the  Linnean  Society/  published  in 
1865.  It  is  here  reproduced  in  a  corrected  and,  I 
hope,  clearer  form,  with  some  additional  facts.  The 
illustrations  were  drawn  by  my  son,  George  Darwin. 
Fritz  Miiller,  after  the  publication  of  my  paper,  sent 
to  the  Linnean  Society  (Journal,  vol.  ix.,  p.  344)  some 
interesting  observations  on  the  climbing  plants  of 
South  Brazil,  to  which  I  shall  frequently  refer. 
Becently  two  important  memoirs,  chiefly  on  the 
difference  in  growth  between  the  upper  and  lower 
sides  of  tendrils,  and  on  the  mechanism  of  the  move- 
ments of  twining  plants,  by  Dr.  Hugo  de  Yries,  have 
appeared  in  the  'Arbeiten  des  Botanischen  Instituts 
in  Wiirzburg,'  Heft,  iii.,  1873.  These  memoirs  ought 
to  be  carefully  studied  by  every  one  interested  in  the 
subject,  as  I  can  here  give  only  references  to  the 
more  important  points.      This  excellent   observer,  as 


Yl  PREFACE. 

well  as  Professor  Sachs,*  attributes  all  the  movements 
of  tendrils  to  rapid  growth  along  one  side ;  but,  from 
reasons  assigned  towards  the  close  of  my  fourth 
chapter,  I  cannot  persuade  myself  that  this  holds 
good  with  respect  to  those  due  to  a  touch.  In  order 
that  the  reader  may  know  what  points  have  interested 
me  most,  I  may  call  his  attention  to  certain  tendril- 
bearing  plants;  for  instance,  Bignonia  capreolata, 
Cobsea,  Echinocystis,  and  Hanburya,  which  display 
as  beautiful  adaptations  as  can  be  found  in  any  part 
of  the  kingdom  of  nature.  It  is,  also,  an  interesting 
fact  that  intermediate  states  between  organs  fitted  for 
widely  different  functions,  may  be  observed  on  the 
same  individual  plant  of  Corydalis  claviculata  and 
the  common  vine;  and  these  cases  illustrate  in  a 
striking  manner  the  principle  of  the  gradual  evolu- 
tion of  species. 


*  An    English    translation    of  of  Text-Book  of  Botany,' and  this 

the  '  Lehrbuch  dcr  Botanik  'by  is  a  great  boon  to  all  lovers  of 

Professor     Sachs,    has    recently  natural  science  in  England. 
(1875),  appeared  under  the  title 


CONTENTS. 


CHAPTEK  I. 

Twining  Plants. 

Introductory  remarks — Description  of  the  twining  of  tlie  Hop 
— Torsion  of  tlie  stems — Nature  of  the  revolving  movement 
and  manner  of  ascent — Stems  not  irritable — Eate  of  revolu- 
tion in  various  plants  —  Thickness  of  the  support  round 
which  plants  can  twine — Species  which  revolve  in  an  anoma- 
lous manner       Pages  1-M 

CHAPTEE  II. 

Leaf-Climbeks. 

Plants  which  climb  by  the  aid  of  spontaneously  revolving  and 
sensitive  petioles — Clematis — Tropceolum — 3IaHrandia,Qo'wev- 
pedmicles  moving  spontaneously  and  sensitive  to  a  touch — 
BJiodocliiton — Lopliospermum,  internodes  sensitive — Solanum, 
thickening  of  the  clasped  petioles  —  Fumaria  —  Adlumia — 
Plants  which  climb  by  the  aid  of  their  produced  midribs — 
Gloriosa  —  Flagellaria  —  Nepenthes  —  Summary  on  leaf- 
climbers    45-83 

CHAPTER  III. 

Tendeil-Beaeers. 

Nature  of  tendrils — Bignoniaoe^,  various  species  of,  and  their 
different  modes  of  climbing — Tendrils  which  avoid  the  light, 
and  creep  into  crevices — Development  of  adhesive  discs — 
Excellent  adaptations  for  seizing  different  kinds  of  supports 
—  PoLEMONiACEiE  —  Cdbcea  scandens,  much  branched  and 


Vlll  CONTENTS. 

hooked  tendrils,  their  manner  of  action  —  Leguminos^  — 
Composite  —  Smilace^  —  Smilax  aspera,  its  ineflficient 
tendrils  —  Fumakiace^  —  Corydalis  daviculata,  its  state 
intermediate  between  that  of  a  leaf-climber  and  a  tendril- 
bearer     Pages  84-126 

CHAPTEE   IV. 

Tendril-Beakers — continued. 

CucuRBiTACE^  —  HomologoTis  nature  of  the  tendrils — Echino- 
cystis  lohata,  remarkable  movements  of  the  tendrils  to  avoid 
seizing  the  terminal  shoot — Tendrils  not  excited  by  contact 
with  other  tendrils  or  by  di'ops  of  water — Undulatory  move- 
ment of  the  extremity  of  the  tendril — Eanlurya,  adherent 
discs  —  ViTAOE^  —  Gradation  between  the  flower-peduncles 
and  tendrils  of  the  vine — Tendrils  of  the  Virginian  Creeper 
turn  from  the  light,  and  after  contact  develop  adhesive 
discs  —  Sapindace^— Passiplorace^ — Passiflora  gracilis  — 
Eapid  revolving  movement  and  sensitiveness  of  the  tendrils 
— Not  sensitive  to  the  contact  of  other  tendrils  or  of  drops  of 
water  —  Spiral  contraction  of  tendrils  —  Summary  on  the 
natixre  and  action  of  tendrils ,.     127-182 


CHAPTER   V. 

Hook  and  Eoot-Climbers. — Concluding  Eemarks. 

Plants  climbing  by  the  aid  of  hooks,  or  merely  scrambling  over 
other  plants — Eoot-climbers,  adhesive  matter  secreted  by  the 
rootlets — General  conclusions  with  respect  to  climbing  plants, 
and  the  stages  of  their  development       183-206 


Index 207 


yllaimed  Wherever  Fouiict.  I 
"D     HAiJiTS" 


CLIMBING  PLANTS. 


CHAPTER    I. 

Twining  Plants. 

Introductory  remarks — Description  of  the  twining  of  the  Hop — Torsion 
of  the  stems — Nature  of  the  revolving  movement,  and  manner  of 
ascent — Stems  not  ii'ritable — Eate  of  revolution  in  various  plants — 
Thickness  of  the  support  round  which  plants  can  twine — Species 
which  revolve  in  an  anomalous  manner. 

I  WAS  led  to  this  subject  by  an  interesting,  but  short 
paper  by  Professor  Asa  Gray  on  the  movements  of  the 
tendrils  of  some  Cucurbitaceous  plants.*  My  obser- 
vations were  more  than  half  completed  before  I  learnt 
that  the  surprising  phenomenon  of  the  spontaneous 
revolutions  of  the  stems  and  tendrils  of  climbins: 
plants  had  been  long  ago  observed  by  Palm  and  by 
Hugo  von  Mohljt  and  had  subsequently  been  the 
subject  of  two  memoirs  by  Dutrochet.^     Nevertheless, 


*  '  Proc.  Amer.  Acad,  of  Arts  pflanzen,'  1827.     Palm's  Treatise 

and   Sciences,'   vol.  iv.  Aug.  12,  was  published  only  a  few  weeks 

1858,  p.  98.  before  Mohl's.    See  also  '  The  Ve- 

t  Ludwig  H.  Palm,  '  Ueber  das  getable  Cell '  (translated  by  Hen- 

Winden  der  Pflanzen ; '  Hugo  von  frey),  by  H.  von  Mohl,  p.  147  to 

Mohl,  '  Ueber  den  Bau  und   das  end. 

Wiuden  der  Kanken  und  Schling-  %  "  Des  Mouvements  revolutifs 


2  TWINING    PLANTS.  Chap.  I, 

.1  believe  that  my  observations,  founded  on  the  ex- 
amination ,  of  above  a  hundred  widely  distinct  living 
species,  contain  sufficient  novelty  to  justify  me  in 
publishing  them. 

Climbing  plants  may  be  divided  into  four  classes, 
rirst,  those  which  twine  spirally  round  a  support,  and 
are  not  aided  by  any  other  movement.  Secondly, 
those  endowed  with  irritable  organs,  which  when  they 
touch  any  object  clasp  it;  such  organs  consisting  of 
modified  leaves,  branches,  or  flower-peduncles.  But 
these  two  classes  sometimes  graduate  to  a  certain 
extent  into  one  another.  Plants  of  the  third  class 
ascend  merely  by  the  aid  of  hooks ;  and  those  of  the 
fourth  by  rootlets ;  but  as  in  neither  class  do  the  j)lants 
exhibit  any  special  movements,  they  present  little 
interest,  and  generally  when  I  speak  of  climbing  plants 
I  refer  to  the  two  first  great  classes. 

TvriNiNG  Plants. 

This  is  the  largest  subdivision,  and  is  apparently 
the  primordial  and  simplest  condition  of  the  class. 
My  observations  will  be  best  given  by  taking  a  few 
special  cases.  When  the  shoot  of  a  Hop  {Sumulus 
lupulus)  rises  from  the  ground,  the  two  or  three  first- 
formed  joints  or  internodes  are  straight  and  remain 
stationary ;   but  the  next-formed,  whilst  very  young, 


Bpontanes,"&c., 'ComptesEendus,'      cherches    sur    la  Yolubilite    des 
torn.  xvii.   (1843)  p.   989;  "Ee-      Tiges,"&c.,tom.xis.(18ii)p.295. 


Chap.  I.  TWINING   PLANTS.  3 

may  be  seen  to  bend  to  one'  side  and  to  travel  slowly 
round  towards  all  points  of  the  caanpass,  moving,  like 
the  hands  of  a  watch,  with  the  sun.  The  movement 
very  soon  acquires  its  full  ordinary  velocity.  From 
seven  observations  made  during  August  on  shoots  pro- 
ceeding from  a  plant  which  had  been  cut  down,  and  on 
another  plant  during  April,  the  average  rate  during  hot 
weather  and  during  the  day  is  2  hrs.  8  m.  for  each  revo- 
lution ;  and  none  of  the  revolutions  varied  much  from 
this  rate.  The  revolving  movement  continues  as  long 
as  the  plant  continues  to  grow ;  but  each  separate 
internode,  as  it  becomes  old,  ceases  to  move. 

To*  ascertain  more  precisely  what  amount  of  move- 
ment each  internode  underwent,  I  kept  a  potted  plant, 
during  the  night  and  day,  in  a  well-warmed  room  to 
which  I  was  confined  by  illness.  A  long  shoot  pro- 
jected beyond  the  upper  end  of  the  supporting  stick, 
and  was  steadily  revolving.  I  then  took  a  longer  stick 
and  tied  up  the  shoot,  so  that  only  a  very  young  inter- 
node, 1|  of  an  inch  in  length,  was  left  free.  This  was  so 
nearly  upright  that  its  revolution  could  not  be  easily 
observed  ;  but  it  certainly  moved,  and  the  side  of  the 
internode  which  was  at  one  time  convex  became  concave, 
which,  as  we  shall  hereafter  see,  is  a  sure  sign  of  the 
revolving  movement.  I  will  assume  that  it  made  at 
least  one  revolution  during  the  first  twenty -four  hours. 
Early  the  next  morning  it%  position  was  marked,  and  it 
made  a  second  revolution  in  9  hrs. ;  during  the  latter 
part  of  this  revolution  it  moved  much  quicker,  and  the 
third  circle  was  performed  in  the  evening  in  a  little  over 


4  TWINING  PLANTS.  Chap.  I. 

3  hrs.  As  on  the  succeeding  morning  I  found  that  the 
shoot  revolved  in  2  brs.  45  m.,  it  must  have  made  during 
the  night  four  revolutions,  each  at  the  average  rate  of 
a  little  over  3  hrs.  I  should  add  that  the  temperature 
of  the  room  varied  only  a  little.  The  shoot  had  now 
grown  3^  inches  in  length,  and  carried  at  its  extremity 
a  young  internode  1  inch  in  length,  which  showed 
slight  changes  in  its  curvature.  The  next  or  ninth 
revolution  was  effected  in  2  hrs.  30  m.  From  this  time 
forward,  the  revolutions  were  easily  observed.  The 
thirty-sixth  revolution  was  performed  at  the  usual 
rate  ;  so  was  the  last  or  thirty-seventh,  but  it  was  not 
completed ;  for  the  internode  suddenly  became  upright, 
and  after  moving  to  the  centre,  remained  motionless. 
I  tied  a  Aveight  to  its  upper  end,  so  as  to  bow  it  slightly 
and  thus  detect  any  movement ;  but  there  was  none. 
Some  time  before  the  last  revolution  was  half  performed, 
the  lower  part  of  the  internode  ceased  to  move. 

A  few  more  remarks  will  complete  all  that  need  be 
said  about  this  internode.  It  moved  during  five 
days;  but  the  more  rapid  movements,  after  the  per- 
formance of  the  third  revolution,  lasted  during  three 
days  and  twenty  hours.  The  regular  revolutions, 
from  the  ninth  to  thirty-sixth  inclusive,  were  effected 
at  the  average  rate  of  2  hrs.  31  m. ;  but  the  weather  was 
cold,  and  this  affected  the  temperature  of  the  room, 
especially  during  the  night,  and  consequently  retarded 
the  rate  of  movement  a  little.  There  was  only  one 
irregular  movement,  which  consisted  in  the  stem  rapidly 
making,  after  an  unusually  slow  revolution,  only  the 


Chap,  I.  TWINING  PLANTS.  5 

segment  of  a  circle.  After  the  seventeenth  revolution 
the  internode  had  grown  from  If  to  6  inches  in  length, 
and  carried  an  internode  1|  inch  long,  which  was 
just  perceptibly  moving ;  and  this  carried  a  very  minute 
ultimate  internode.  After  the  twenty-first  revolution, 
the  penultimate  internode  was  2^  inches  long,  and 
probably  revolved  in  a  period  of  about  three  hours. 
At  the  twenty-seventh  revolution  the  lower  and  still 
moving  internode  was  8|,  the  penultimate  3^,  and 
the  ultimate  2^  inches  in  length  ;  and  the  inclination 
of  the  whole  shoot  was  such,  that  a  circle  19  inches 
in  diameter  was  swept  by  it.  When  the  movement 
ceased,  the  lower  internode  was  9  inches,  and  the 
penultimate  6  inches  in  length;  so  that,  from  the 
twenty-seventh  to  thirty-seventh  revolutions  inclusive, 
three  internodes  were  at  the  same  time  revolving. 

The  lower  internode,  when  it  ceased  revolving, 
became  upright  and  rigid ;  but  as  the  whole  shoot 
was  left  to  grow  unsupported,  it  became  after  a  time 
bent  into  a  nearly  horizontal  position,  the  uppermost 
and  growing  internodes  still  revolving  at  the  extremity, 
but  of  course  no  longer  round  the  old  central  point  of 
the  supporting  stick.  From  the  changed  position 
of  the  centre  of  gravity  of  the  extremity,  as  it  revolved, 
a  slight  and  slow  swaying  movement  was  given  to  the 
long  horizontally  projecting  shoot ;  and  this  movement 
I  at  first  thought  was  a  spontaneous  one.  As  the  shoot 
grew,  it  hung  down  more  and  more,  whilst  the  growing 
andxevolving  extremity  turned  itself  up  more  and  more. 

With  the  Hop  we  have  seen  that  three  internodes 


6  TWINING  PLANTS.  Chap.  1. 

were  at  the  same  time  revolving  ;  and  this  was  the  case 
with  most  of  the  plants  observed  by  me.  With  all,  if  in 
full  health,  two  intemodes  revolved;  so  that  by  the  time 
tlie  lower  one  ceased  to  revolve,  the  one  above  was  in 
full  action,  with  a  terminal  internode  just  commencing 
to  move.  With  Soya  carnosa,  on  the  other  hand,  a 
depending  shoot,  without  any  developed  leaves,  32 
inches  in  length,  and  consisting  of  seven  intemodes 
(a  minute  terminal  one,  an  inch  in  length,  being 
counted),  continually,  but  sloAvly,  swayed  from  side 
to  side  in  a  semicircular  course,  with  the  extreme 
intemodes  making  complete  revolutions.  This  sway- 
ing movement  was  certainly  due  to  the  movement  of 
the  lower  intemodes,  which,  however,  had  not  force 
sufficient  to  swing  the  whole  shoot  round  the  central 
supj)orting  stick.  The  case  of  another  Asclepiadaceous 
plant,  viz.,  Ceropegia  Gardnerii,  is  worth  briefly  giving. 
I  allowed  the  top  to  grow  out  almost  horizontally  to 
the  length  of  31  inches ;  this  now  consisted  of  three 
long  intemodes,  terminated  by  two  short  ones.  The 
whole  revolved  in  a  course  opposed  to  the  sun  (the 
reverse  of  that  of  the  Hop),  at  rates  between  5  hrs.  15  m. 
and  6  hrs.  45  m.  for  each  revolution.  The  extreme  tip 
thus  made  a  circle  of  above  5  feet  (or  62  inches)  in  dia- 
meter and  16  feet  in  circumference,  travelling  at  the 
rate  of  32  or  33  inches  per  hour.  The  weather  being 
hot,  the  plant  was  allowed  to  stand  on  my  study-table  ; 
and  it  was  an  interesting  spectacle  to  watch  the  long 
shoot  sweeping  this  grand  cricle,  night  and  day,  in 
search  of  some  object  round  which  to  twine. 


CuAp.  I.  TWINING   PLANTS.  7 

If  we  take  hold  of  a  growing  sapling,  we  can  of 
course  bend  it  to  all  sides  in  succession,  so  as  to  make 
the  tip  describe  a  circle,  like  that  performed  by  the 
summit  of  a  spontaneously  revolving  plant.  By  this 
movement  the  sapling  is  not  in  the  least  twisted 
round  its  own  axis.  I  mention  this  because  if  a  black 
point  be  painted  on  the  bark,  on  the  side  which  is 
uppermost  when  the  sapling  is  bent  towards  the 
holder's  body,  as  the  circle  is  described,  the  black 
point  gradually  turns  round  and  sinks  to  the  lower 
side,  and  comes  up  again  when  the  circle  is  completed  ; 
and  this  gives  the  false  appearance  of  twisting,  which, 
in  the  case  of  spontaneously  revolving  plants,  deceived 
me  for  a  time.  The  appearance  is  the  more  deceitful 
because  the  axes  of  nearly  all  twining-plants  are 
really  twisted ;  and  they  are  twisted  in  the  same 
direction  with  the  spontaneous  revolving  movement. 
To  give  an  instance,  the  internode  of  the  Hop  of 
which  the  history  has  been  recorded,  was  at  first,  as 
could  be  seen  by  the  ridges  on  its  surface,  not  in  the 
least  twisted ;  but  when,  after  the  37th  revolution,  it 
had  grown  9  inches  long,  and  its  revolving  movement 
had  ceased,  it  had  become  twisted  three  times  round 
its  own  axis,  in  the  line  of  the  course  of  the  sun ;  on 
the  other  hand,  the  common  Convolvulus,  which 
revolves  in  an  opposite  course  to  the  Hop,  becomes 
twisted  in  an  opposite  direction. 

Hence  it  is  not  surprising  that  Hugo  von  Mohl 
(p.  105,  108,  &c.)  thought  that  the  twisting  of  the 
axis  caused  the  revolving  movement ;    but  it  is  not 


8  TWINING  PLANTS.  Chap.  I 

jjossible  that  the  twisting  of  the  axis  of  the  Hop  three 
times  should  have  caused  thirty-seven  revolutions. 
Moreover,  the  revolving  movement  commenced  in  the 
young  internode  before  any  twisting  of  its  axis  could 
be  detected.  The  internodes  of  a  young  Siphomeris 
and  Lecontea  revolved  during  several  days,  but  became 
twisted  only  once  round  their  own  axes.  The  best 
evidence,  however,  that  the  twisting  does  not  cause  the 
revolving  movement  is  aiforded  by  many  leaf-climbing 
and  tendril-bearing  plants  (as  Pisum  sativum,  Echino- 
cystis  Idbata,  Bignonia  capreolata,  Eccremoearpus  scaher, 
and  with  the  leaf-climbers,  Solanum  jasminoides  and 
various  species  of  Clematis),  of  which  the  internodes  are 
not  twisted,  but  which,  as  we  shall  hereafter  see,  re- 
gularly perform  revolving  movements  like  those  of  true 
twining-plants.  Moreover,  according  to  Palm  (pp.  30, 
95)  and  Mohl  (p.  149),  and  Leon,*  internodes  may 
occasionally,  and  even  not  very  rarely,  be  found  which 
are  twisted  in  an  opposite  direction  to  the  other  inter- 
nodes on  the  same  plant,  and  to  the  course  of  their 
revolutions ;  and  this,  according  to  Leon  (p.  356),  is 
the  case  with  all  the  internodes  of  a  certain  variety  of 
Phaseolus  miiUiflorus.  Internodes  which  have  become 
twisted  round  their  own  axes,  if  they  have  not  ceased 
to  revolve,  are  still  capable  of  twining  round  a  support, 
as  I  have  several  times  observed. 

Mohl  has  remarked  (p.  Ill)  that  when  a  stem  twines 
round  a  smooth  cylindrical  stick,  it  does  not  become 


*  'Bull.  Bot  Soc.  de  France,'  torn.  v.  1858,  p.  356. 


Chap.  I.  TWINING   PLANTS.  9 

twisted.*  Accordingly  I  allowed  kidney-beans  to  run 
up  stretched  string,  and  up  smooth  rods  of  iron  and 
glass,  one-third  of  an  inch  in  diameter,  and  they 
became  twisted  only  in  that  degree  which  follows  as  a 
mechanical  necessity  from  the  spiral  winding.  The 
stems,  on  the  other  hand,  which  had  ascended  ordinary 
rough  sticks  were  all  more  or  less  and  generally  much 
twisted.  The  influence  of  the  roughness  of  the  support 
in  causing  axial  twisting  was  well  seen  in  the  stems 
which  had  twined  up  the  glass  rods ;  for  these  rods 
were  fixed  into  split  sticks  below,  and  were  secured 
above  to  cross  sticks,  and  the  stems  in  passing  these 
places  became  much  twisted.  As  soon  as  the  stems 
which  had  ascended  the  iron  rods  reached  the  summit 
and  became  free,  they  also  became  twisted ;  and  this 
apparently  occurred  more  quickly  during  windy  than 
during  calm  weather.  Several  other  facts  could  be  given, 
showing  that  the  axial  twisting  stands  in  some  relation 
to  inequalities  in  the  support,  and  likewise  to  the  shoot 
revolving  freely  without  any  sujDport.  Many  plants, 
which  are  not  twiners,  become  in  some  degree  twisted 
round  their  own  axes  ;  f  but  this  occurs  so  much  more 


*  This  whole  subject  has  been  it  has  ceased  or  begun  to  cease  in 

ably  discussed  and  explained  by  the  inner  laj'^ers." 
H.   de  Vries,  'Arbeiten   des  Bot.  f  Professor  Asa  Gray  has  re- 

Instituts    in  "Wurzburg,'  Heft  iii.  marked  to  me,  in  a  letter,  that  in 

pp.  331,336.  See  also  Sachs  ('Text-  Thuja  occidentalis  the  twisting  of 

Book  of  Botany,'  English  transla-  the  bark  is  very  conspicuous.     The 

tion,  1 875,  p.  770),  who  concludes  twist  is  generally  to  the  right  of 

"  that  torsion  is  the  result  of  growth  the    observer ;  but,     in    noticing 

continuing  in  the  outer  layers  after  about  a  hundred  trunks,  four  or 


10  TWINING   PLANTS.  Chap.  I. 

generally  and  strongly  with  twining-jDlants  than  with 
other  plants,  that  there  must  be  some  connexion 
between  the  capacity  for  twining  and  axial  twisting. 
The  stem  probably  gains  rigidity  by  being  twisted 
(on  the  same  principle  that  a  much  twisted  rope  is 
stiffer  than  a  slackly  twisted  one),  and  is  thus  in- 
directly benefited  so  as  to  be  enabled  to  pass  over 
inequalities  in  its  spiral  ascent,  and  to  carry  its  own 
weight  when  allowed  to  revolve  freely.* 

I  have  alluded  to  the  twisting  which  necessarily 
follows  on  mechanical  principles  from  the  spiral 
ascent  of  a  stem,  namely,  one  twist  for  each  spire 
completed.  This  was  well  shown  by  painting  straight 
lines  on  living  stems,  and  then  allowing  them  to  twine ; 
but,  as  I  shall  have  to  recur  to  this  subject  under 
Tendrils,  it  may  be  here  jDassed  over. 

The  revolving  movement  of  a  twining  plant  has 
been  compared  with  that  of  the  tip  of  a  sapling,  moved 
round  and  round  by  the  hand  held  some  way  down 
the  stem ;  but  there  is  one  important  difference. 
The   upper   part    of   the   sapling   when   thus    moved 


five  were  observed  to  be  twisted  marked  to  me  in  a  letter  tliat 
in  an  opposite  direction.  Tlie  "  some  of  these  cases,  if  not  all, 
Spanish  chestnut  is  often  much  are  dependent  upon  some  obstacle 
twisted :  there  is  an  interesting  or  resistance  to  their  upward 
article  on  this  subject  in  the  growth."  This  conclusion  agrees 
'Scottish  Farmer,'  1865,  p.  833.  with  what  I  have  said  about  the 
*  It  is  well  known  that  the  twisting  of  stems,  which  have 
stems  of  many  plants  occasionally  twined  round  rugged  supports ; 
become  spirally  twisted  in  a  but  does  not  preclude  the  twist- 
monstrous  manner ;  and  after  my  ing  being  of  service  to  the  plant 
paper  was  read  before  the  Linncan  by  giving  greater  rigidity  to  the 
Society.  Dr.  Maxwell  Masters  re-  stem. 


Chap.  I.  TWINING   PLANTS.  1 1 

remains  straight ;  but  with  twining  plants  every  part 
of  the  reyolving  shoot  has  its  own  separate  and 
independent  movement.  This  is  easily  proved ;  for 
when  the  lower  half  or  two-thirds  of  a  long  revolving 
shoot  is  tied  to  a  stick,  the  upper  free  part  continues 
steadily  revolving.  Even  if  the  whole  shoot,  except 
an  inch  or  two  of  the  extremity,  be  tied  up,  this  part, 
as  I  have  seen  in  the  case  of  the  Hop,  Ceropegia, 
Convolvulus,  &c.,  goes  on  revolving,  but  much  more 
slowly ;  for  the  internodes,  until  they  have  grown  to 
some  little  length,  always  move  slowly.  If  we  look  to 
the-  one,  two,  or  several  internodes  of  a  revolving  shoot, 
they  will  be  all  seen  to  be  more  or  less  bowed,  either 
during  the  whole  or  during  a  large  part  of  each  revolu- 
tion. Now  if  a  coloured  streak  be  painted  (this  was 
done  with  a  large  number  of  twining  plants)  along, 
we  will  say,  the  convex  surface,  the  streak  will  after 
a  time  (depending  on  the  rate  of  revolution)  be 
found  to  be  running  laterally  along  one  side  of  the 
bow,  then  along  the  concave  side,  then  laterally  on 
the  opposite  side,  and,  lastly,  again  on  the  originally 
convex  surface.  This  clearly  proves  that  during  the 
revolving  movement  the  internodes  become  bowed 
in  every  direction.  The  movement  is,  in  fact,  a  con- 
tinuous self-bowing  of  .the  whole  shoot,  successively 
directed  to  all  points  of  the  compass ;  and  has  been 
well  designated  by  Sachs  as  a  revolving  nutation. 

As  this  movement  is  rather  difficult  to  understand, 
it  will  be  well  to  give  an  illustration.  Take  a  sapling 
and  bend  it  to  the  south,  and  paint  a  black  line  on  the 


12  TWINING   PLANTS.  Chap.  I. 

convex  surface  ;  let  the  sapling  spring  up  and  bend  it 
to  the  east,  and  the  black  line  will  be  seen  to  run 
along  the  lateral  face  fronting  the  north ;  bend  it  to 
the  north,  the  black  line  will  be  on  the  concave 
surface  ;  bend  it  to  the  west,  the  line  will  again  be  on 
the  lateral  face ;  and  when  again  bent  to  the  south, 
the  line  will  be  on  the  original  convex  surface.  Now, 
instead  of  bending  the  sapling,  let  us  suppose  that  the 
cells  along  its  northern  surface  from  the  base  to  the 
tip  were  to  grow  much  more  rapidly  than  on  the  three 
other  sides,  the  whole  shoot  would  then  necessarily  be 
bowed  to  the  south  ;  and  let  the  longitudinal  growing 
surface  creep  round  the  shoot,  deserting  by  slow  degrees 
the  northern  side  and  encroaching  on  the  western  side, 
and  so  round  by  the  south,  by  the  east,  again  to  the 
north.  In  this  case  the  shoot  would  remain  always 
bowed  with  the  painted  line  appearing  on  the  several 
above  specified  surfaces,  and  with  the  point  of  the 
shoot  successively  directed  to  each  point  of  the 
compass.  In  fact,  we  should  have  the  exact  kind  of 
movement  performed  by  the  revolving  shoots  of  twining 
plants.* 

It  must  not  be  supposed  that  the  revolving  move- 
ment is  as  regular  as  that  given  in  the  above  illustra- 
tion ;  in  very  many  cases  the  tip  describes  an  ellipse, 
even  a  very  narrow  ellipse.     To  recur  once  again  to 


*  The  view  that  the  revolving  H.  de  Vries;  and  the  truth  of  this 

movement  or  nutation  of  the  stems  view  is  proved  by  their  excellent 

of  twining  plants  is  due  to  growth  observations. 
is  that  advanced  by   Sachs  and 


Chap.  I.  TWINING   PLANTS.  13 

our  illustration,  if  we  suppose  only  the  northern  and 
southern  surfaces  of  the  sapling  alternately  to  grow 
rapidly,  the  summit  would  describe  a  simple  arc ;  if 
the  growth  first  travelled  a  very  little  to  the  western 
face,  and  during  the  return  a  very  little  to  the  eastern 
face,  a  narrow  ellipse  would  be  described ;  and  the 
sapling  would  be  straight  as  it  passed  to  and  fro 
through  the  intermediate  space ;  and  a  complete 
straightening  of  the  shoot  may  often  be  observed  in 
revolving  plants.  The  movement  is  frequently  such 
that  three  of  the  sides  of  the  shoot  seem  to  be  growing 
in  due  order  more  rapidly  than  the  remaining  side  ;  so 
that  a  semi-circle  instead  of  a  circle  is  described,  the 
shoot  becoming  straight  and  upright  during  half  of  its 
course. 

When  a  revolving  shoot  consists  of  several  inter- 
nodes,  the  lower  ones  bend  together  at  the  same  rate, 
but  one  or  two  of  the  terminal  ones  bend  at  a  slower 
rate ;  hence,  though  at  times  all  the  internodes  are 
in  the  same  direction,  at  other  times  the  shoot  is 
rendered  slightly  serpentine.  The  rate  of  revolution 
of  the  whole  shoot,  if  judged  by  the  movement  of  the 
extreme  tip,  is  thus  at  times  accelerated  or  retarded. 
One  other  point  must  be  noticed.  Authors  have  ob- 
served that  the  end  of  the  shoot  in  many  twining  plants 
is  completely  hooked  ;  this  is  very  general,  for  instance, 
with  the  Asclepiadaceae.  The  hooked  tip,  in  all  the 
cases  observed  by  me,  viz.  in  Cerojpegia,  Sphserostema, 
Clerodendron,  Wistaria,  Stejohania,  AJiehia,  and  Sipho- 
meris,  has  exactly  the  same  kind  of  movement  as  the 


J  4  TWINING  PL.\NTS.  Chap.  L 

other  internodes ;  for  a  line  painted  on  the  convex 
surface  first  becomes  lateral  and  then  concave ;  but, 
owing  to  the  youth  of  these  terminal  internodes,  the 
reversal  of  the  hook  is  a  slower  process  than  that  of  the 
revolving  movement.*  This  strongly  marked  tendency 
in  the  young,  terminal  and  flexible  internodes,  to  bend 
in  a  greater  degree  or  more  abruptly  than  the  other 
internodes,  is  of  service  to  the  plant ;  for  not  only  does 
the  hook  thus  formed  sometimes  serve  to  catch  a 
support,  but  (and  this  seems  to  be  much  more  impor- 
tant) it  causes  the  extremity  of  the  shoot  to  embrace 
the  support  much  more  closely  than  it  could  otherwise 
have  done,  and  thus  aids  in  preventing  the  stem  from 
being  blown  away  during  windy  weather,  as  I  have 
many  times  observed.  In  Lonicera  hraehypoda  the 
hook  only  straightens  itself  periodically,  and  never 
becomes  reversed.  I  will  not  assert  that  the  tips  of 
all  twining  plants  when  hooked,  either  reverse  them- 
selves or  become  periodically  straight,  in  the  manner 
just  described  ;  for  the  hooked  form  may  in  some  cases 
be  permanent,  and  be  due  to  the  manner  of  growth  of 
the  species,  as  with  the  tips  of  the  shoots  of  the  com- 
mon vine,  and  more  plainly  with  those  of  Cissus  dis- 
color— plants  which  are  not  spiral  twiners. 

The   first    purpose    of    the   spontaneous   revolving 
movement,    or,   more   strictly   speaking,   of  the   con- 


*  The  mechanism  by  which  the  H.  de  Vries  (ibid.  p.  337)  :  he 
eud  of  the  shoot  remains  hooked  concludes  that  "  it  depends  on  the 
appears  to  be  a  difficult  and  relationbetweenthe  rapidity  of  tor- 
complex  problem,  discussed  by  Dr.  sion  and  the  rapidity  of  nutation.'' 


Chap.  I.  TWINING  PLANTS.  15 

tinuous  Lowing  movement  directed  successively  to  all 
points  of  the  compass,  is,  as  Mohl  has  remarked,  to 
favour  the  shoot  finding  a  support.  This  is  admirably- 
effected  by  the  revolutions  carried  on  night  and  day, 
a  wider  and  wider  circle  being  swept  as  the  shoot 
increases  in  length.  This  movement  likewise  explains 
how  the  plants  twine ;  for  when  a  revolving  shoot 
meets  with  a  support,  its  motion  is  necessarily  arrested 
at  the  point  of  contact,  but  the  free  projecting  part 
goes  on  revolving.  As  this  continues,  higher  and 
higher  points  are  brought  into  contact  with  the 
support  and  are  arrested ;  and  so  onwards  to  the  ex- 
tremity ;  and  thus  the  shoot  winds  round  its  support. 
When  the  shoot  follows  the  sun  in  its  revolving 
course,  it  winds  round  the  support  from  right  to  left, 
the  support  being  suj)posed  to  stand  in  front  of  the 
beholder ;  when  the  shoot  revolves  in  an  opposite 
direction,  the  line  of  winding  is  reversed.  As  each 
internode  loses  from  age  its  power  of  revolving,  it  like- 
wise loses  its  power  of  spirally  twining.  If  a  man 
swings  a  rope  round  his  head,  and  the  end  hits  a  stick, 
it  will  coil  round  the  stick  according  to  the  direction 
of  the  swinging  movement ;  so  it  is  with  a  twining  plant, 
a  line  of  growth  travelling  round  the  free  part  of  the 
shoot  causing  it  to  bend  towards  the  opposite  side,  and 
this  replaces  the  momentum  of  the  free  end  of  the  rope. 
All  the  authors,  except  Palm  and  Mohl,  who  have 
discussed  the  spiral  twining  of  plants,  maintain  that 
such  plants  have  a  natural  tendency  to  grow  spirally. 
Mohl    believes   (p.    112)    that   twining    stems    have 


16  TWINING   PLANTS.  Chap.  I 

a  dull  kind  of  irritability,  so  that  they  bend  towards 
any  object  which  they  touch ;  but  this  is  denied 
by  Palm.  Even  before  reading  Mohl's  interesting 
treatise,  this  view  seemed  to  me  so  probable  that  I 
tested  it  in  every  way  that  I  could,  but  always  with 
a  negative  result.  I  rubbed  many  shoots  much  harder 
than  is  necessary  to  excite  movement  in  any  tendril 
or  in  the  foot-stalk  of  any  leaf  climber,  but  without  any 
effect.  I  then  tied  a  light  forked  twig  to  a  shoot  of  a 
Hop,  a  Coropegia,  SiDlixrostema,  and  Adhatoda,  so  that 
the  fork  pressed  on  one  side  alone  of  the  shoot  and 
revolved  with  it ;  I  purposely  selected  some  very  slow 
revolvers,  as  it  seemed  most  likely  that  these  would 
profit  most  from  possessing  irritability  ;  but  in  no  case 
was  any  effect  produced.*  Moreover,  when  a  shoot 
winds  round  a  support,  the  winding  movement  is 
always  slower,  as  we  shall  immediately  see,  than 
whilst  it  revolves  freely  and  touches  nothing.  Hence 
I  conclude  that  twining  stems  are  not  irritable ;  and 
indeed  it  is  not  probable  that  they  should  be  so,  as 
nature  always  economizes  her  means,  and  irritability 
would  have  been  superfluous.  Nevertheless  I  do  not 
wish  to  assert  that  they  are  never  irritable;  for  the 
growing  axis  of  the  leaf-climbing,  but  not  spirally 
twining,  Lopliospermum  seandens  is,  certainly  irritable ; 
but  this  case  gives  me  confidence  that  ordinary  twiners 


*  Dr.    H.    de    Vries  also  has  plants  are  not  irritable,  and  that 

shown  (ibid.  p.  321  and  325)  by  a  the  cause  of  their  winding  up  a 

better  method  than  that  employed  support  is  exactly  what  I  have  de- 

by  me,  that  the  stems  of  twining  scribed. 


Chap.  I.  TWINING   PLANTS.  17 

do  not  possess  any  such  quality,  for  directly  after 
putting  a  stick  to  the  Lojpliosioermum,  I  saw  that  it 
behaved  differently  from  a  true  twiner  or  any  other 
leaf-climber.* 

The  belief  that  twiners  have  a  natural  tendency  to 
grow  spirally,  probably  arose  from  their  assuming  a 
spiral  form  when  wound  round  a  support,  and  from  the 
extremity,  even  whilst  remaining  free,  sometimes 
assuming  this  form.  The  free  internodes  of  vigor- 
ously growing  plants,  when  they  cease  to  revolve, 
become  straight,  and  show  no  tendency  to  be  spiral ; 
but  when  a  shoot  has  nearly  ceased  to  grow,  or  when 
the  plant  is  unhealthy,  the  extremity  does  occasionally 
become  spiral.  I  have  seen  this  in  a  remarkable 
manner  with  the  ends  of  the  shoots  of  the  Stauntonia  and 
of  the  allied  Akehia,  which  became  wound  up  into  a  close 
spire,  just  like  a  tendril ;  and  this  was  apt  to  occur  after 
some  small,  ill-formed  leaves  had  perished.  The  ex- 
planation, I  believe,  is,  that  in  such  cases  the  lower  parts 
of  the  terminal  internodes  very  gradually  and  suc- 
cessively lose  their  power  of  movement,  whilst  the 
portions  just  above  move  onwards  and  in  their  turn 
become  motionless ;  and  this  ends  in  forming  an 
irregular  spire. 

When  a  revolving  shoot  strikes  a  stick,  it  winds 
round  it  rather  more  slowly  than  it  revolves.  For 
instance,  a  shoot  of  the  Cero]pegia,  revolved  in  6  hrs., 


t  Dr.  H.  de  Vries  states  (ibid.  p.  322)  that  the  stem  of  Cuscuta  is 
irritable  like  a  tendril. 
2 


18  TWINING  PLANTS.  Chap.  L 

but  took  9  hrs.  30  m.  to  make  one  complete  spire  round 
a  stick  ;  Aristolocliia  gigas  revolved  in  about  5  lirs.,  but 
took  9  lirs.  15  m.  to  complete  its  sjDire.  This,  I  presume, 
is  due  to  the  continued  disturbance  of  the  impelling 
force  by  the  arrestment  of  the  movement  at  successive 
points  ;  and  we  shall  hereafter  see  that  even  shaking  a 
plant  retards  the  revolving  movement.  The  terminal 
internodes  of  a  long,  much-inclined,  revolving  shoot  of 
the  Ceropegia,  after  they  had  wound  round  a  stick, 
always  slipped  up  it,  so  as  to  render  the  spire  more 
open  than  it  was  at  first ;  and  this  was  probably  in 
part  due  to  the  force  which  caused  the  revolutions, 
being  now  almost  freed  from  the  constraint  of  gravity 
and  allowed  to  act  freely.  With  the  Wistaria,  on  the 
other  hand,  a  long  horizontal  shoot  wound  itself  at 
first  into  a  very  close  spire,  which  remained  un- 
changed ;  but  subsequently,  as  the  shoot  twined 
spirally  up  its  support,  it  made  a  much  more  open 
spire.  With  all  the  many  plants  which  were  allowed 
freely  to  ascend  a  support,  the  terminal  internodes 
made  at  first  a  close  spire ;  and  this,  during  windy 
weather,  served  to  keep  the  shoots  in  close  contact 
with  their  support ;  but  as  the  penultimate  internodes 
grew  in  length,  they  pushed  themselves  up  for  a 
considerable  space  (ascertained  by  coloured  marks  on 
the  shoot  and  on  the  support)  round  the  stick,  and  the 
spire  became  more  open.* 

It  follows  from    this   latter  fact  that  the  position 


See  Dr.  H.  de  Vries  (ibid.  p.  324)  on  this  subject. 


CiiAi>.  I.  TWINING   PLANTS.  '-.  19 

occupied  by  each  leaf  with  respect  to  the  support, 
depends  on  the  growth  of  the  internodes  after  they 
have  become  spirally  wound  round  it.  I  mention  this 
on  account  of  an  observation  by  Palm  (p.  34),  who 
states  that  the  opposite  leaves  of  the  Hop  always  stand 
in  a  row,  exactly  over  one  another,  on  the  same  side 
of  the  supporting  stick,  whatever  its  thickness  may 
be.  My  sons  visited  a  hop-field  for  me,  and  reported 
that  though  they  generally  found  the  points  of  inser- 
tion of  the  leaves  standing  over  each  other  for  a  space 
of  two  or  three  feet  in  height,  yet  this  never  occurred 
up  the  whole  length  of  the  pole ;  the  points  of  insertion 
forming,  as  might  have  been  expected,  an  irregular 
spire.  Any  irregularity  in  the  pole  entirely  'destroyed 
the  regularity  of  position  of  the  leaves.  From  casual 
inspection,  it  appeared  to  me  that  the  opposite  leaves 
of  Thunhergia  alata  were  arranged  in  lines  up  the  sticks 
round  which  they  had  twined  ;  accordingly,  I  raised  a 
dozen  plants,  and  gave  them  sticks  of  various  thick- 
nesses, as  well  as  string,  to  twine  round ;  and  in  this 
case  one  alone  out  of  the  dozen  had  its  leaves 
arranged  in  a  perj)endicular  line  :  I  conclude,  therefore, 
Palm's  statement  is  not  quite  accurate. 

The  leaves  of  different  twining-plants  are  arranged 
on  the  stem  (before  it  has  twined)  alternately,  or 
oppositely,  or  in  a  spire.  In  the  latter  case  the  line  of 
insertion  of  the  leaves  and  the  course  of  the  revolutions 
coincide.    This  fact  has  been  well  shown  by  Dutrochet,* 


*  Comptes  Eenclus,  1844,  torn.  xix.  p.  295,  and  Annales  des  Sc.  Nat. 
3rd  series,  Bot.,  torn.  ii.  p.  163. 


20  r  TWINING  PLANTS.  Chap.  L 

who  found  different  individuals  of  Solarium  dulcamara 
twining  in  opposite  directions,  and  these  had  their 
leaves  in  each  case  sj)irally  arranged  in  the  same  direc- 
tion. A  dense  whorl  of  many  leaves  would  apparently 
be  incommodious  for  a  twining  plant,  and  some  authors 
assert  that  none  have  their  leaves  thus  arranged ;  but 
a  twining  8ii)homeris  has  whorls  of  three  leaves. 

If  a  stick  which  has  arrested  a  revolving  shoot,  but 
has  not  as  yet  been  encircled,  be  suddenly  taken 
away,  the  shoot  generally  springs  forward,  showing 
that  it  was  pressing  with  some  force  against  the  stick. 
After  a  shoot  has  wound  round  a  stick,  if  this  be  with- 
drawn, it  retains  for  a  time  its  spiral  form ;  it  then 
straightens  itself,  and  again  commences  to  revolve. 
The  long,  much-inclined  shoot  of  the  Ceropegia  pre- 
viously alluded  to  offered  some  curious  peculiarities. 
The  lower  and  older  internodes,  which  continued  to 
revolve,  were  incapable,  on  repeated  trials,  of  twining 
round  a  thin  stick  ;  showing  that,  although  the  power 
of  movement  was  retained,  this  was  not  sufficient 
to  enable  the  plant  to  twine.  I  then  moved  the 
stick  to  a  greater  distance,  so  that  it  was  struck  by 
a  point  2^  inches  from  the  extremity  of  the  penulti- 
mate internode ;  and  it  was  then  neatly  encircled 
by  this  part  of  the  penultimate  and  by  the  ultimate 
internode.  After  leaving  the  spirally  wound  shoot  for 
eleven  hours,  I  quietly  withdrew  the  stick,  and  in  the 
course  of  the  day  the  curled  portion  straightened 
itself  and  recommenced  revolving ;  but  the  lower  and 
not  curled  portion  of  the  penultimate  internode  did 


Chap.  I.  TWINING   PLANTS.  21 

not  move,  a  sort  of  hinge  separating  the  moving  and 
the  motionless  part  of  the  same  iuternode.  After  a 
few  days,  however,  I  found  that  this  lower  part  had 
likewise  recovered  its  revolving  power.  These  several 
facts  show  that  the  power  of  movement  is  not  immedi- 
ately lost  in  the  arrested  portion  of  a  revolving  shoot ; 
and  that  after  being  temporarily  lost  it  can  be  recovered. 
When  a  shoot  has  remained  for  a  considerable  time 
round  a  support,  it  permanently  retains  its  spiral  form 
even  when  the  support  is  removed. 

When  a  tall  stick  was  placed  so  as  to  arrest  the 
lower  and  rigid  internodes  of  the  Ceropegia,  at  the 
distance  at  first  of  15  and  then  of  21  inches  from  the 
centre  of  revolution,  the  straight  shoot  slowly  and 
gradually  slid  up  the  stick,  so  as  to  become  more  and 
more  highly  inclined,  but  did  not  pass  over  the 
summit.  Then,  after  an  interval  sufficient  to  have 
allowed  of  a  semi-revolution,  the  shoot  suddenly 
bounded  from  the  stick  and  fell  over  to  the  opposite 
side  or  point  of  the  compass,  and  reassumed  its 
previous  slight  inclination.  It  now  recommenced 
revolving  in  its  usual  course,  so  that  after  a  semi- 
revolution  it  again  came  into  contact  with  the  stick, 
again  slid  up  it,  and  again  bounded  from  it  and  fell 
over  to  the  opposite  side.  This  movement  of  the 
shoot  had  a  very  odd  appearance,  as  if  it  were 
disgusted  with  its  failure  but  was  resolved  to  try 
again.  We  shall,  I  think,  understand  this  movement 
by  considering  the  former  illustration  of  the  sapling,  in 
which  the  growing  surface  was  supposed  to  creep  round 


22  TWINING   PLANTS.  Chap.  I. 

from  the  northern  by  the  western  to  the  southern 
face ;  and  thence  back  again  by  the  eastern  to  the 
northern  face,  successively  bowing  the  sapling  in  all 
directions.  Now  with  the  Ceropegia,  the  stick  being 
placed  to  the  south  of  the  shoot  and  in  contact  with 
it,  as  soon  as  the  circulatory  growth  reached  the 
western  surface,  no  effect  would  be  produced,  except  that 
the  shoot  would  be  pressed  firmly  against  the  stick. 
But  as  soon  as  growth  on  the  southern  surface  began, 
the  shoot  would  be  slowly  dragged  with  a  sliding  move- 
ment up  the  stick ;  and  then,  as  soon  as  the  eastern 
growth  commenced,  the  shoot  would  be  drawn  from  the 
stick,  and  its  weight  coinciding  with  the  effects  of  the 
changed  surface  of  growth,  would  cause  it  suddenly  to 
fall  to  the  opposite  side,  reassuming  its  previous  slight 
inclination ;  and  the  ordinary  revolving  movement 
would  then  go  on  as  before.  I  have  described  this 
curious  case  with  some  care,  because  it  first  led  me  to 
understand  the  order  in  which,  as  I  then  thought,  the 
surfaces  contracted ;  but  in  which,  as  we  now  know  from 
Sachs  and  H.  de  Vries,  they  grow  for  a  time  rapidly, 
thus  causing  the  shoot  to  bow  towards  the  opposite 
side. 

The  view  just  given  further  explains,  as  I  believe, 
a  fact  observed  by  Mohl  (p.  135),  namely,  that  a 
revolving  shoot,  though  it  will  twine  round  an  object 
as  thin  as  a  thread,  cannot  do  so  round  a  thick  support. 
I  placed  some  long  revolving  shoots  of  a  Wistaria 
close  to  a  post  between  5  and  6  inches  in  diameter, 
but,  though  aided  by  me  in  many  ways,  they  could 


Chap.  I.  TWINING   PLANTS.  23 

not  wind  round  it.  Tliis  apparently  was  due  to  the 
flexure  of  the  shoot,  whilst  winding  round  an  object 
so  gently  curved  as  this  post,  not  being  sufficient  to 
hold  the  shoot  to  its  place  when  the  growing  surface 
crept  round  to  the  opposite  surface  of  the  shoot ;  so 
that  it  was  withdrawn  at  each  revolution  from  its 
support. 

When  a  free  shoot  has  grown  far  beyond  its  support, 
it  sinks  downwards  from  its  weight,  as  already  explained 
in  the  case  of  the  Hop,  with  the  revolving  extremity 
turned  upwards.  If  the  support  be  not  lofty,  the  shoot 
falls  to  the  ground,  and  resting  there,  the  extremity 
rises  up.  Sometimes  several  shoots,  when  flexible, 
twine  together  into  a  cable,  and  thus  support  one 
another.  Single  thin  depending  shoots,  such  as  those 
of  the  SoUya  Drummondii,  will  turn  abruptly  back- 
wards and  wind  up  on  themselves.  The  greater 
number  of  the  depending  shoots,  however,  of  one 
twining  plant,  the  Hibhertia  dentata,  showed  but  little 
tendency  to  turn  upwards.  In  other  cases,  as  with  the 
Cryiitostegia  grandijiora,  several  internodes  which  were 
at  first  flexible  and  revolved,  if  they  did  not  succeed  in 
twining  round  a  support,  become  quite  rigid,  and  sup- 
porting themselves  upright,  carried  on  their  summits 
the  younger  revolving  internodes. 

Here  will  be  a  convenient  place  to  give  a  Table 
showing  the  direction  and  rate  of  movement  of  several 
twining  plants,  with  a  few  appended  remarks.  These 
plants  are  arranged  according  to  Lindley's  '  Vegetable 
Kingdom  '  of  1853  ;  and  they  have  been  selected  fjom 


24 


TWINING  PLANTS. 


Chap.  L 


all  parts  of  the  series  so  as  to  show  that  all  kinds 
behave  in  a  nearly  uniform  manner.* 

Tlie  Bate  of  Revolution  of  various  Tioining  Plants. 

(ACOTYLEDONS.) 
Lygodium  scandens  (Polypodiacese)  moves  against  the  sun. 


June  18, 1st  circle  was  made  in 
„     18,2nd     „        „        „ 
„     19,3rd      „        „        „ 
„    ly,  4tii     „       „       „ 
„     20,5th      „        „        „ 


H.    M. 

6    0 

6  15  (late  in  evening) 

5  32  (very  hot  day) 

5  0  (very  hot  day) 

6  0 


Lygodium  articulatum  moves  against  the  sun. 

H.    M. 

July  19, 1st  circle  was  made  in    .  16  30  (shoot  very  young) 
„    20,2nd      „        „        „         .   15    0 
„    21,3rd       „        „        „         .80 
„    22, 4th       „        „        „        .  10  30 

• 
(Monocotyledons.) 

Muscus  androgynus  (Liliaceee),  placed  in  the  hot-house,  moves 
against  the  sun. 


n.  M. 

May  24, 1st  circle 

was  made  in 

6  14  (shoot  very  young) 

„     25, 2nd 

»        }i 

2  21 

„     25, 3rd 

»                    !> 

3  37 

„     25, 4th 

)>                    » 

3  22 

„     26, 5th 

»           >y 

2  50 

„     27, 6th 

>>           )> 

3  52 

„     27, 7th 

)}           1} 

4  11 

*  I  am  much  indebted  to  Dr. 
Hooker  for  having  sent  me  many 
plants  from  Kew;  and  to  Mr. 
Veitch,  of  the  Koyal  Exotic  Nur- 
sery, for  having  generously  given 
me  a  collection  of  fine  specimens 


of  climbing  plants.  Professor  Asa 
Gray,  Prof  Oliver,  and  Dr.  Hooker 
have  aftbrded  me,  as  on  niany 
previous  occabions,  much  infor- 
mation and  many  references. 


Chap. 


TWINING   PLANTS. 


25 


(Mo'NOCOTyIjEBO^s,  continued.) 
Asparagus  (unnamed  species  from   Kew)  (Liliaceai)  moves 
against  the  sun,  placed  in  hothouse. 

H.       M. 

Dec,  26, 1st  circle  was  made  in  .     .     .50 
„    27, 2nd    „        „        „        ...     5  40 
Tamus  communis  (Dioscoreacese).    A  young    shoot  from  a 
tuber  in  a  pot  placed  in  the  greenhouse  :  follows  the  sun. 

H.    U. 

3  10 


July,  7, 1st  circle  was  made  in 
„     7,2nd     „ 
„     o,  3rd      „        „        „ 
»     o>  4th      „        „        „ 
„     o,  5th      „        „        „ 
„     8, 6th      „        „        „ 

Laparjerea  rosea  (Philesiacese),  in  greenhouse,  follows  the  sun. 

H.      M. 

March    9, 1st  circle  was  made  in  .      .  26  15  (shoot  young) 

10,  semicircle    „        „        .     .     8  15 

11,  2ud  circle    „        „ 
12,3rd      „ 
13,4th      „        „ 
16, 5th     „        „        „ 

the  hothoixse ;  but  the  next  day  the  shoot  remained 
stationary. 

Eoxburghia  viridiflora  (Eoxburghiacese)  moves  against  the 
sun ;  it  completed  a  circle  in  about  24  hours. 

(Dicotyledons.) 
Eumulus  Lupulus  (Urticacese)  follows  the  sun.     The  plant 


2  38 

3  5 
2  56 
2  30 
2  30 


11    0 
15  30 
14  15 
8  40  when  placed  in 


XAX    tX    L\J\JiA±    KX\X 

iiiijj  >i 

ai.UA 

I    »y  cci  tJLitii . 

H.     M. 

April    9,  2  cii 

cles  were 

made  in  . 

.  4  16 

Aug.  13,3rd 

circle 

was 

>> 

.  2    0 

„     14, 4th 

» 

» 

.  2  20 

„     14, 5th 

» 

y>             • 

.     .  2  16 

„     14,6th 

)) 

» 

.  2    2 

„     14,  7th 

» 

}> 

.  2    0 

„     14, 8th 

„ 

}>             • 

.  2    4 

26  TWINING  PLANTS.  Chap.  I. 

(Dicotyledons,  continued.) 

With  the  Hop  a  semicircle  was  performed,  in  travelling 
from  the  light,  in  1  hr.  33  m. ;  in  travelling  to  the  light,  in 
1  hr.  13  m. ;  difference  of  rate,  20  m. 

Ahtbia  quinata  (Lardizabalacese),  placed  in  hothouse,  moves 
against  the  sun. 

H.      M. 

March  17, 1st  circle  was  made  in  .  .40  (shoot  young) 

„      18, 2nd       „        „        „  .  .  1  40 

„      18, 3rd       „        „        „  .  .  1  30 

„     19, 4th       „        „        „  .  .  1  45 

Btauntonia  latifolia  (Lardizabalacese),  placed    in    hothouse, 
moves  against  the  sun. 

IT.     M 

March  28, 1st  circle  was  made  in      .     .  3  30 
„     29, 2nd    „        „        „  .     .  3  45 

Sphcerostema  marmoratum  (Schizandracese)  follows  the  sun. 

H.     M. 

August  5th,  1st  circle  was  made  in  about      .     .  24    0 
„      5th,  2nd  circle  was  made  in    .     .     .     .  18  30 

Stephania  rotunda  (Menispermacefe)  moves  against  the  sun. 


May  27, 1st  circle  was  made  in    . 

..55 

„    30,2nd     „        „        „ 

..76 

June  2, 3rd      „        „        „ 

.     .  5  15 

„      o,  4tu       „         „         „ 

.      .   6  28 

Tliryallis  Iracliystachys  (Malpighiacese)  moves  against  the  sun : 
one  shoot  made  a  circle  in  12  hrs.,  and  another  in  10  hrs.  30  m. ; 
but  the  next  day,  which  was  much  colder,  the  first  shoot  took 
10  hrs.  to  perform  only  a  semicircle. 

Eihhertia  dentata  (Dilleniacefe),  placed  in  the  hothouse,  fol- 
lowed the  sun,  and  made  (May  18th)  a  circle  in  7  hrs.  20  m. ;  on 
the  19th,  reversed  its  course,  and  moved  against  the  sun,  and 
made  a  circle  in  7  hrs. ;  on  the  20th,  moved  against  the  sun  one- 
tlxird  of  a  circle,  and  then  stood  still ;  on  the  26th,  followed  the 


Chap.  1, 


TWINING   PLANTS. 


27 


(Dicotyledons,  continued.) 

sun  for  two-tbirds  of  a  circle,  and  then  returned  to  its  starting- 
point,  taking  for  this  double  course  11  brs.  46  m. 

SoUya  Drummondii  (Pittosporaceae)  moves  against  the  sun; 
kept  in  greenhouse. 


H.      H. 

4  25 

8    0  (very  cold  day) 

6  25 

7  5 


April  4, 1st  circle  was  made  in 
„    5, 2ud      „ 
„    D,  ord       „        „        „ 
„    7,4th      „ 

Polygonum  dumetorum  (Polygonacese).  This  case  is  taken 
from  Dutrochet  (p.  299),  as  I  observed,  no  allied  plant :  follows 
the  sun.  Three  shoots,  cut  off  a  plant,  and  placed  in  water, 
made  circles  in  3  hrs.  10  m.,  5  hrs.  20  m.,  and  7  hrs.  15  m. 

Wistaria  Chinensis  (Leguminosas),  in  greenhouse,  moves 
against  the  sun. 

H.     M. 

3    5 


13,  2nd 

.     .  3  20 

16,  3rd 

)                    »                    )> 

..25 

24,  4th 

,                    „                    „ 

.     .  3  21 

25,  5th 

>                   »                   }> 

.     .  2  37 

25,  6th 

>                   })                   )> 

.     .  2  35 

Phaseolus  vulgaris  (Leguminosse),  in  greenhouse,  moves  against 
the  sun. 

ir.    M. 

May,  1st  circle  was  made  in    .     .     .     .20 
„     2nd     „        „        „        ....  1  55 
„     3rd     „        „        „        ....  1  55 
Dipladenia  uro;pliylla  (Apocynacese)  moves  against  the  sun. 

H.      M. 

April  18, 1st  circle  was  made  in  .     .     .80 
„     19,2nd     „        „        „      .     . 
„     oO,  3rd      „        „        „       .     . 

Tipladenia  crassinoda  moves  against  the  sun. 

May  16, 1st  circle  was  made  in    . 
•      July  20, 2nd     „        „        „ 

„     21, 3rd      „        „        „        .     . 


9  15 

9  40 

H. 

M. 

9 

5 

8 

0 

8 

5 

28  TWINING   PLANTS.  Cuap.  I. 

(Dicotyledons,  continued.) 
Ctropegia  Gardnerii  (Asclepiadaceje)  moves  against  the  sun. 

H.      M. 

Shoot  very  young,  2  inches K  ,     .    ,  „         ,  .      _  -c- 

.    ,        ,    "^       °  >  1st  circle  was  performed  m    7  55 

m  length ) 

Shoot  still  young 

Long  shoot 

Long  shoot     . 

Long  shoot     . 


Stephanotis  florihu 


2ad  „  „  „  „  7    0 

3rd  „  „  „  „  6  33 

4th  „  „  „  „  5  L5 

5th  „  ,,  „  „  0  45 


ida  (Asclepiadacese)  moves  against  the  sun 


and  made  a  circle  in  6  hrs.  40  m.,  a  second  circle  in  about  9  hrs. 

lloya  carnosa  (Asclepiadacere)  made  several  circles  in  from 
16  hrs.  to  22  hrs.  or  24  hrs. 

Ipomcea  purpurea  (Convolvulaceae)  moves  against  the  sun. 
Plant  placed  in  room  with  lateral  light. 

i Semicircle,  from  the  light  in 
1  hr.  14  m.,  to  the  light 
1  hr .  28  m. :  difference  14  m. 
I  Semicircle,  from  the  light  in 
1  hi-.  17  m.,  to  the  light  1  hr. 
30  m. :  difference  13  m. 

Ipom(Ba  jucunda  (Convolvulaceae)  moves  against  the  sun,  placed 
in  my  study,  with  windows  facing  the  north-east.     Weather  hot. 

I  Semicircle,  from  the  light  in 
4  hrs.  30  m.,  to  the  hght  1  hr. 
0  m. :  difference  3  hrs.  30  m. 

2nd  circle  was  made  in  5  hrs.  j  Semicircle,  from  the  light  in 
20  m.  (Late  m  afternoon :  I  3  ^^^.^  5q  ^^  ^^  ^j^^  j.gj^^  ^  j^j,_ 
circle  completed  at  6  hrs.  40  m.      3^^  .  aiffcrence  2  hrs  20  m. 

P.M.)  I 

We  have  here  a  remarkable  instance  of  the  power  of  light  in 
retarding  and  hastening  the  revolving  movement. 

Convolvulus  septum  (large-flowered  cultivated  var.)  moves 
against  the  sun.  Two  circles,  were  made  each  in  1  hr.  42  m. : 
difference  in  semicircle  from  and  to  the  light  14  m. 


CuAP.  I.  TWINING   PLANTS.  29 

(Dicotyledons,  continued.) 

liivea  tiJicefoUa  (Convolvulacece)  moves  against  the  siin; 
made  four  revolutions  in  9  hrs. ;  so  that,  on  an  average,  each 
was  performed  in  2  hrs.  15  m. 

Plumbago  rosea  (Plumbaginacere)  follows  the  sun.  The  shoot 
did  not  begin  to  revolve  until  nearly  a  yard  in  height ;  it  then 
made  a  fine  cii'cle  in  10  hrs.  45  m.  During  the  next  few  days  it 
continued  to  move,  but  irregularly.  On  August  15th  the  shoot 
followed,  during  a  period  of  IQ  hrs.  40  m.,  a  long  and  deeply 
zigzag  course  and  then  made  a  broad  ellipse.  The  figure 
apparently  represented  three  ellipses,  each  of  which  averaged 
3  hrs.  33  m.  for  its  completion. 

Jasminum  pauciflorum,  Bentham  (Jasminacese),  moves  against 
the  sun.  A  circle  was  made  in  7  hrs.  15  m.,  and  a  second  rather 
more  quickly. 

Clerodendrum  Thomsonii  (Verbenacese)  follows  the  sun. 

H.     M. 

April  12,  1st  circle  was  made  in  .     5  45  (shoot  very  young) 
„     14, 2nd    „        „        „        .     3  30 

((directly  after  the 
plant  was  shaken 
on  being  moved) 
„     19, 3rd  cii-cle    „        „        .30 
„     20,4th     „        „        „        .4  20 

Tecoma  jasminoides  (Bignoniacese)  moves  against  the  sun. 

H.      M. 

March  17,  1st  circle  was  made  in  .     6  30 

„      19,2ud    „        „        „  .70 

„      22, 3rd     „        „        „  .8  30  (very  cold  day) 

„      24, 4th     „        „        „  .6  45 

T/nmhergia  alata  (Acanthacese)  moves  against  sun. 

H.       M. 

April  14,  1st  circle  was  made  in  .  3  20 
„  18,  2ud  „  „  „  .2  50 
„  18, 3rd  „  „  „  .2  55 
„     18,  4th     „        „        „        .3  55  (late  in  afternoon) 


30 


TWINING  PLANTS. 


Chap.  I. 


(Dicotyledons,  continued.) 

Adhadota  cydonoefolia  (Acantliacefe)  follows  the  sun.  A  young 
shoot  made  a  semicircle  in  24  hrs. ;  subsequently  it  made  a 
circle  in  between  40  hrs.  and  48  hxs.  Another  shoot,  however, 
made  a  circle  in  26  hrs.  30  m. 

Mikania  scandens  (Compositse)  moves  against  the  sun. 

H.       M. 

March  14, 1st  circle  was  made  in  3  10 


AprU 


15,  2ud 

16,  3rd 

17,  4th 

7,5th 

7,6th 


3  0 
3  0 
3  33 

2  50 


2  40 


1  This  circle  was  made 
after  a  copious  water- 
ing with  cold  water  at 
47°  Fahr. 


Comhretum  argenteum  (Combretacese)  moves  against  the  sua. 
Kept  iu  hothouse. 

H.       H. 

i Early  in    morning,  when 
the  temperatiu-e  of  the 
house  had  fallen  a  little. 
„    24,  '^  CKCles  eacli  at  an  i 
average  of .     .     . ) 
„    25,  4th  circle  was  made  in  2  25 

Comhretum  jpurpureum  revolves  not  quite  so  quickly  as  C. 
arge7iteum. 

Loasa  aurantiaca  (Loasaceae).    Eevolutious  variable  in  tho'r 
course :  a  plant  which  moved  against  the  sun. 

H.     M. 

June  20, 1st  circle  was  made  in  .     .     .  2  37 

20, 2nd    „        „        „  ...  2  13 

20,3rd     „        „        „  ...  4    0 

21, 4th     „        „        „  ...  2  35 

22, 5th     „        „        „  ...  3  26 

23,6th     „        „        „  ...  3    5 


Chap.  I. 


TWINING   PLANTS. 


31 


(Dicotyledons,  continued.) 
Another  jjlant  which  followed  the  sun  in  its  revolutions. 


July  11, 1st  circle  was  ma 

de  in    .     .     .  1  51 

„    11,2nd     „ 

„        ...  1  46 

■  Very  1 

„    11, 3rd      „  ,     „ 

„        ...  1  41 

„    11,4th       „        „ 

„        ...  1  48 

„    12,5th     „        „ 

„        ...  2  35 

Scyphanthus  elegans  (Loasace£E)  follows  the  sun. 

H.    H. 

June  13, 1st  circle  was  made  in  .     .     .     1  45 

„    13,2nd    „ 

„       „        ...    117 

,,    14,3rd    „ 

„       ;,       ...    136 

„    14,4th    „ 

»        „        ...     1  59 

„    14,5th    „ 

39                  }>                   •            • 

/■ T        .  __     \       /T^'.    _ 

.     2    3 

Siphomeris  or  Lecontea  (unnamed  sp.)  (Cinchcnaceae)  follows 
the  sun. 


May  25,  semicircle  was  made  in 


„ 

26, 

2st  ci) 

■cle 

» 

30, 

2nd 

)> 

June  2, 

3rd 

„ 

» 

G, 

4th 

3) 

» 

8, 

5th 

» 

» 

9, 

6th 

» 

10  27  J  (s^oo^' ^^ti'ei'^sly 

I    young) 
10  15  (shoot  still  young) 
8  55 


8  11 

6  8 

7  20 

8  36 


Taken  from  the 
hothouse,  and 
placed  in  a  room 
in  my  house. 


Manettia  hicolor  (Cinchonacese),  young  plant,  follows  the  sun. 

H.      M. 

.     6  18 


July  7, 1st  circle  was  made  in 
„     8, 2nd      „        „        „ 
„    J,  ord      „        „        ,, 


6  53 
6  30 


lonicera  hrachypoda  (Caprifoliacese)  follows  the  sun,  kept  in  a 
warm  room  ia  the  house. 

n.     M. 

April,  1st  cii'cle  was  made  in  .     9  10  (about) 


4th    „        „        „        .80-^ 


32  TWINING  PLANTS.  Chap.  I. 

(Dicotyledons,  continued.) 

H.       JI. 

■     M  o   1    •    1  1    •      1  o  nn  I  (a  distinct  shoot,  very 

April,  2nd  cu'cle  was  made  in    12  20  <  ^  ,     ,"; 

[  young,  on  same  plant) 

„      3rd     „        „        „        .7  30 

In   this  latter    circle, 

the  semicircle  from 

the  Hght  took  5  hrs. 

23  m.,  and    to    the 

light  2  hrs.  37  min. : 

[   difference  2  hrs  46  m. 

AristoJochia  gigas  (Aristolochiacese)  moves  against  the  sim. 

H.    u. 

July  22,  1st  circle  was  made  in    .     8    0  (rather  young  shoot) 
„    23, 2nd    „        „        „  .7  15 

„    24, 3rd     „        „        „  .50  (about) 

In  the  foregoing  .Table,  which  includes  twining 
plants  belonging  to  widely  different  orders,  we  see 
that  the  rate  at  which  growth  travels  or  circulates 
round  the  axis  (on  which  the  revolving  movement 
depends),  differs  much.  As  long  as  a  plant  remains 
under  the  same  conditions,  the  rate  is  often  remarkably 
uniform,  as  with  the  Hop,  Mihania,  Phaseolus,  &c.  The 
Scyphanthus  made  one  revolution  in  1  hr.  17  m.,  and 
this  is  the  quickest  rate  observed  by  me  ;  but  we  shall 
hereafter  see  a  tendril-bearing  Passiflora  revolving 
more  rapidly.  A  shoot  of  the  Akebia  quinafa  made  a 
revolution  in  1  hr.  30  m.,  and  three  revolutions  at  the 
average  rate  of  1  hr.  38  m. ;  a  Convolvulus  made  two 
revolutions  at  the  average  of  1  hr.  42  m.,  and  Phaseolus 
vulgaris  three  at  the  average  of  1  hr.  57  m.  On  the 
other  hand,  some  plants  take  24  hrs.  for  a  single 
revolution,  and  the  Adhadota  sometimes  required 
48  hrs. ;  yet  this  latter  plant   is   an   efficient  twiner. 


Chap.  I.  TWINING  PLANTS.  33 

Species  of  the  same  genus  move  at  different  rates. 
The  rate  does  not  seem  governed  by  the  thickness  of 
the  shoots  :  those  of  the  SoUija  are  as  thin  and  flexible 
as  string,  but  move  more  slowly  than  the  thick  and 
fleshy  shoots  of  the  Bicscus,  which  seem  little  fitted  for 
movement  of  any  kind.  The  shoots  of  the  Wistaria, 
which  become  woody,  move  faster  than  those  of  the 
herbaceous  Ipomoea  or  Thunbergia. 

We  know  that  the  internodes,  whilst  still  very 
young,  do  not  acquire  their  proper  rate  of  movement ; 
hence  the  several  shoots  on  the  same  plant  may  some- 
times be  seen  revolving  at  different  rates.  The  two  or 
three,  or  even  more,  internodes  which  are  first  formed 
above  the  cotyledons,  or  above  the  root- stock  of  a 
perennial  plant,  do  not  move  ;  they  can  support  them- 
selves, and  nothing  superfluous  is  granted. 

A  greater  number  of  twiners  revolve  in  a  course 
opposed  to  that  of  the  sun,  or  to  the  hands  of  a  watch, 
than  in  the  reversed  course,  and,  consequently,  the 
majority,  as  is  well  known,  ascend  their  supports  from 
left  to  right.  Occasionally,  though  rarely,  plants  of 
the  same  order  twine  in  opposite  directions,  of  which 
Mohl  (p.  125)  gives  a  case  in  the  Leguminosae,  and  we 
have  in  the  table  another  in  the  Acanthaceas.  I  have 
seen  no  instance  of  two  species  of  the  same  genus 
twining  in  opposite  directions,  and  such  cases  must  be 
rare  ;  but  Fritz  Miiller  *  states  that  although  MiJcania 


*  Journal  of  the  Linn.  Soc.  interesting  paper,  in  which  he 
(Bot.)  vol.  ix.  p.  344.  I  shall  corrects  or  confirms  various  state- 
have  occasion  often  to  quote  this      meuts  made  by  me. 


34  TWINING   PLANTS.  Chap.  I. 

scandens  twines,  as  I  have  described,  from  left  to  right, 
another  species  in  South  Brazil  twines  in  an  opposite 
direction.  It  would  have  been  an  anomalous  circum- 
stance if  no  such  cases  had  occurred,  for  different 
individuals  of  the  same  species,  namely,  of  Solatium 
dulcamara  (Dutrochet,  tom.  xix.  p.  299),  revolve  and 
twine  in  two  directions  :  this  plant,  however,  is  a  most 
feeble  twiner.  Loasa  aurantiaca  (Leon,  p.  351)  offers 
a  much  more  curious  case  :  I  raised  seventeen  plants : 
of  these  eight  revolved  in  opposition  to  the  sun  and 
ascended  from  left  to  right ;  five  followed  the  sun  and 
ascended  from  right  to  left ;  and  four  revolved  and 
twined  first  in  one  direction,  and  then  reversed  their 
course,*  the  petioles  of  the  opposite  leaves  affording  a 
jpoint  d'a])imi  for  the  reversal  of  the  spire.  One  of 
these  four  plants  made  seven  spiral  turns  from  right 
to  left,  and  five  turns  from  left  to  right.  Another 
plant  in  the  same  family,  the  Scyjplianilius  elegans, 
habitually  twines  in  this  same  manner.  I  raised 
many  plants  of  it,  and  the  stems  of  all  took  one 
turn,  or  occasionally  two  or  even  three  turns  in 
one  direction,  and  then,  ascending  for  a  short  space 
straight,  reversed  their  course  and  took  one  or  two 
turns  in  an  opposite  direction.  The  reversal  of 
the  curvature  occurred  at  any  point  in  the  stem, 
even  in  the  middle  of  an  internode.  Had  T  not 
seen  this  case,  I  should  have  thought  its  occurrence 


*  I  raised  nine  plants  of  the      of  these  also  reversed  their  spire 
hybrid   Loasa  Herhertii,  and  six      ia  ascending  a  support. 


Chap.  I.  TWINING   PLANTS,  35 

most  improbable.  It  would  be  hardly  possible  with 
any  plant  which  ascended  above  a  few  feet  in  height, 
or  which  lived  in  an  exposed  situation ;  for  the  stem 
could  be  pulled  away  easily  from  its  support,  with  but 
little  unwinding ;  nor  could  it  have  adhered  at  all, 
had  not  the  internodes  soon  become  moderately  rigid. 
With  leaf-climbers,  as  we  shall  soon  see,  analogous 
cases  frequently  occur  ;  but  these  present  no  difficulty, 
as  the  stem  is  secured  by  the  clasping  petioles. 

In  the  many  other  revolving  and  twining  plants 
observed  by  me,  I  never  but  twice  saw  the  movement 
reversed  ;  once,  and  only  for  a  short  space,  in  Ipomoea 
jucunda  ;  but  frequently  with  Hibhertia  dentata.  This 
plant  at  first  perplexed  me  much,  for  I  continually 
observed  its  long  and  flexible  shoots,  evidently  well 
fitted  for  twining,  make  a  whole,  or  half,  or  quarter 
circle  in  one  direction  and  then  in  an  opposite 
direction ;  consequently,  when  I  placed  the  shoots 
near  thin  or  thick  sticks,  or  perpendicularly  stretched 
string,  they  seemed  as  if  constantly  trying  to  ascend, 
but  always  failed.  I  then  surrounded  the  plant  with  a 
mass  of  branched  twigs ;  the  shoots  ascended,  and 
passed  through  them,  but  several  came  out  laterally,  and 
their  depending  extremities  seldom  turned  upwards  as 
is  usual  with  twining  plants.  Finally,  I  surrounded 
a  second  plant  with  many  thin  upright  sticks,  and 
placed  it  near  the  first  one  with  twigs ;  and  now 
both  had  got  what  they  liked,  for  they  twined  up 
the  parallel  sticks,  sometimes  winding  round  one  and 
sometimes  round   several ;   and   the  shoots  travelled 


36  TWINING  PLANTS.  Chap.  I, 

laterally  from  one  to  the  other  pot ;  but  as  the 
plants  grew  older,  some  of  the  shoots  twined  regu- 
larly up  thin  upright  sticks.  Though  the  revolving 
movement  was  sometimes  in  one  direction  and  some- 
times in  the  other,  the  twining  was  invariably  from 
left  to  right  ;*  so  that  the  more  potent  or  persistent 
movement  of  revolution  must  have  been  in  opposition 
to  the  course  of  the  sun.  It  would  appear  that  this 
Hibhertia  is  adapted  both  to  ascend  by  twining,  and  to 
ramble  laterally  through  the  thick  Australian  scrub. 

I  have  described  the  above  case  in  some  detail, 
because,  as  far  as  I  have  seen,  it  is  rare  to  find  any 
special  adaptations  with  twining  plants,  in  which 
respect  they  differ  much  from  the  more  highly  organ- 
ized tendril-bearers.  The  Solanum  dulcamara,  as  we 
shall  presently  see,  can  twine  only  round  stems  which 
are  both  thin  and  flexible.  Most  twining  plants  are 
adapted  to  ascend  supports  of  moderate  though  of 
different  thicknesses.  Our  English  twiners,  as  far  as 
I  have  seen,  never  twine  round  trees,  excepting  the 
honeysuckle  (Lonicera  perichjmenuni),  which  I  have 
observed  twining  up  a  young  beech-tree  nearly  4^ 
inches  in  diameter.  Mohl  (p.  134)  found  that  the 
Phaseolus  multijiorus  and  Ipomoea  purpurea  could  not, 


*   In    another   genus,    namely  left ;  and  I  once  saw  a  shoot  which 

Davilla,  belonging   to  the    same  ascended  a  tree  about  five  inches 

family     with     Hibbertia,      Fritz  in  diameter,  reverse  its  course  in 

Miiller    says  (ibid.  p.   349)   that  the  same  manner  as  so  frequently 

"  the    stem    twines    indifferently  occurs  with  Loasa." 
from  left  to  right,  or  from  right  to 


Chap.  I.  TWINING   PLANTS.  37 

when  placed  in  a  room  with  the  light  entering  on  one 
side,  twine  ronnd  sticks  between  3  and  4  inches  in 
diameter ;  for  this  interfered,  in  a  jnanner  presently 
to  be  explained,  with  the  revolving  movement.  In  the 
open  air,  however,  the  Phaseolus  twined  round  a 
support  of  the  above  thickness,  but  failed  in  twining 
round  one  9  inches  in  diameter.  Nevertheless,  some 
twiners  of  the  warmer  temperate  regions  can  manage 
this  latter  degree  of  thickness ;  for  I  hear  from 
Dr.  Hooker  that  at  Kew  the  Buscus  androgynus  has 
ascended  a  column  9  inches  in  diameter  ;  and  although 
a  Wistaria  grown  by  me  in  a  small  pot  tried  in  vain 
for  weeks  to  get  round  a  post  between  5  and  6  inches 
in  thickness,  yet  at  Kew  a  plant  ascended  a  trunk 
above  6  inches  in  diameter.  The  tropical  twiners,  on 
the  other  hand,  can  ascend  thicker  trees  ;  I  hear  from 
Drs.  Thomson  and  Hooker  that  this  is  the  case  with 
the  Butea  ]}arvifiora,  one  of  the  Menispermacea?,  and 
with  some  Dalbergias  and  other  Leguminosse.*  This 
power  would  be  necessary  for  any  species  which  had 
to  ascend  by  twining  the  large  trees  of  a  tropical  forest ; 
otherwise  they  would  hardly  ever  be  able  to  reach  the 
light.  In  our  temperate  countries  it  would  be  injurious 
to  the  twining  plants  which  die  down  every  year  if 


*  Fritz  Miiller  states  (ibid.  p.  ispermacese.  He  adds  ia  his 
349)  that  he  saw  on  one  occasion  in  letter  to  me  that  most  of  the 
the  forests  of  South  Brazil  a  trunk  climbing  plants  which  there 
about  five  feet  in  circumference  ascend  thick  trees,  are  root- 
spirally  ascended  by  a  plant,  climbers  ;  some  being  tendril- 
apparently  belonging  to  the  Men-  bearers. 


38  TWINING  PLANTS.  Chap.  I. 

they  were  enabled  to  twine  round  trunks  of  trees,  for 
they  could  not  grow  tall  enough  in  a  single  season  to 
reach  the  summit  and  gain  the  light. 

By  what  means  certain  twining  plants  are  adapted  to 
ascend  only  thin  stems,  whilst  others  can  twine  round 
thicker  ones,  I  do  not  know.  It  appeared  to  me 
probable  that  twining  plants  with  very  long  revolving 
shoots  would  be  able  to  ascend  thick  supports ;  accord- 
ingly I  placed  Ceropegia  Gardnerii  near  a  post  6 
inches  in  diameter,  but  the  shoots  entirely  failed  to 
wind  round  it ;  their  great  length  and  power  of  move- 
ment merely  aid  them  in  finding  a  distant  stem 
round  which  to  twine.  The  Sphserostemma  marmora- 
tum  is  a  vigorous  tropical  twiner ;  and  as  it  is  a  very 
slow  revolver,  I  thought  that  this  latter  circumstance 
might  help  it  in  ascending  a  thick  support ;  but  though 
it  was  able  to  wind  round  a  6-inch  post,  it  could  do 
this  only  on  the  same  level  or  plane,  and  did  not 
form  a  spire  and  thus  ascend. 

As  ferns  differ  so  much  in  structure  from  phanero- 
gamic plants,  it  may  be  worth  while  here  to  show  that 
twining  ferns  do  not  differ  in  their  habits  from  other 
twining  plants.  In  Lygodium  articulaium  the  two 
internodes  of  the  stem  (properly  the  rachis)  which 
are  first  formed  above  the  root-stock  do  not  move ; 
the  third  from  the  ground  revolves,  but  at  first  very 
slowly.  This  species  is  a  slow  revolver :  but  L. 
scandens  made  five  revolutions,  each  at  the  average 
rate  of  5  hrs.  45  m. ;  and  this  represents  fairly  well  the 
usual  rate,  taking  quick  and  slow  movers,  amongst 


Chap.  I.  TWINING   PLANTS,  39 

phanerogamic  plants.  The  rate  was  accelerated  by 
increased  temperature.  At  each  stage  of  growth  only 
the  two  upper  internodes  revolved.  A  line  painted 
along  the  convex  surface  of  a  revolving  internode 
becomes  first  lateral,  then  concave,  then  lateral  and 
ultimately  again  convex.  Neither  the  internodes  nor 
the  petioles  are  irritable  when  rubbed.  The  movement 
is  in  the  usual  direction,  namely,  in  opposition  to  the 
course  of  the  sun  ;  and  when  the  stem  twines  round  a 
thin  stick,  it  becomes  twisted  on  its  own  axis  in  the  same 
direction.  After  the  young  internodes  have  twined 
round  a  stick,  their  continued  growth  causes  them  to 
slip  a  little  upwards.  If  the  stick  be  soon  removed, 
they  straighten  themselves,  and  recommence  revolving. 
The  extremities  of  the  depending  shoots  turn  upwards, 
and  twine  on  themselves.  In  all  these  respects  we 
have  complete  identity  with  twining  phanerogamic 
plants ;  and  the  above  enumeration  may  serve  as  a 
summary  of  the  leading  characteristics  of  all  twining 
plants. 

The  power  of  revolving  depends  on  the  general 
health  and  vigour  of  the  plant,  as  has  been  laboriously 
shown  by  Palm.  But  the  movement  of  each  separate 
internode  is  so  independent  of  the  others,  that  cutting 
off  an  upper  one  does  not  affect  the  revolutions  of  a 
lower  one.  When,  however,  Dutrochet  cut  off  two 
whole  shoots  of  the  Hop,  and  placed  them  in  water,  the 
movement  was  greatly  retarded ;  for  one  revolved  in 
20  hrs.  and  the  other  in  23  hrs.,  whereas  they  ought 
to  have  revolved  in  between  2  hrs.  and  2  hrs.  30  m. 


40  TWINING   PLANTS.  Chap.  I. 

Shoots  of  the  Kidney-bean,  cut  off  and  placed  in 
water,  were  similarly  retarded,  but  in  a  less  degree. 
I  have  repeatedly  observed  that  carrying  a  plant  from 
the  greenhouse  to  ~my  room,  or  from  one  part  to 
another  of  the  greenhouse,  always  stopped  the  move- 
ment for  a  time ;  hence  I  conclude  that  plants  in  a 
state  of  nature  and  growing  in  exposed  situations, 
would  not  make  their  revolutions  during  very  stormy 
weather.  A  decrease  in  temperature  always  caused  a 
considerable  retardation  in  the  rate  of  revolution ;  but 
Dutrochet  (tom.  xvii.  pp.  994,  996)  has  given  such 
precise  observations  on  this  head  with  respect  to  the 
common  pea  that  I  need  say  nothing  more.  When 
twining  plants  are  placed  near  a  window  in  a  room, 
the  light  in  some  cases  has  a  remarkable  power 
{as  was  likewise  observed  by  Dutrochet,  p.  998,  with 
the  pea)  on  the  revolving  movement,  but  this  differs 
in  degree  with  different  plants  ;  thus  Ipomoea  jucunda 
made  a  complete  circle  in  5  hrs.  30  m. ;  the  semi- 
circle from  the  light  taking  4  hrs.  30  m.,  and  that 
towards  the  light  only  1  hr.  Lonicera  hracliyijoda 
revolved,  in  a  reversed  direction  to  the  Iiwmoea,  in 
8  hrs. ;  the  semicircle  from  the  light  taking  5  hrs.  23  m., 
and  that  to  the  light  only  2  hrs.  37  m.  From  the 
rate  of  revolution  in  all  the  plants  observed  by  me, 
being  nearly  the  same  during  the  night  and  the 
day,  I  infer  that  the  action  of  the  light  is  confined  to 
retarding  one  semicircle  and  accelerating  the  other, 
so  as  not  to  modify  greatly  the  rate  of  the  whole 
revolution.      This  action  of  the  light  is  remarkable, 


Chap.  I.  TWINING   PLANTS.  41 

when  we  reflect  how  little  the  leaves  are  developed  on 
the  young  and  thin  revolving  internodes.  It  is  all 
the  more  remarkable,  as  botanists  believe  (Mohl, 
p.  119)  that  twining  plants  are  but  little  sensitive 
to  the  action  of  light. 

I  will  conclude  my  account  of  twining  plants  by 
giving  a  few  miscellaneous  and  curious  cases.  With 
most  twining  plants  all  the  branches,  however  many 
there  may  be,  go  on  revolving  together;  but,  ac- 
cording to  Mohl  (p.  4),  only  the  lateral  branches  of 
Tamus  elephantipes  twine,  and  not  the  main  stem. 
On  the  other  hand,  with  a  climbing  species  of  Aspa- 
ragus, the  leading  shoot  alone,  and  not  the  branches, 
revolved  and  twined  ;  but  it  should  be  stated  that  the 
plant  was  not  growing  vigorously.  My  plants  of 
Comhretum  argenteum  and  G.  purpureum  made  nume- 
rous short  healthy  shoots  ;  but  they  showed  no  signs 
of  revolving,  and  I  could  not  conceive  how  these 
plants  could  be  climbers  ;  but  at  last  C.  argenteum  put 
forth  from  the  lower  part  of  one  of  its  main  branches 
a  thin  shoot,  5  or  6  feet  in  length,,  differing  greatly 
in  appearance  from  the  previous  shoots,  owing  to  its 
leaves  being  little  developed,  and  this  shoot  re- 
volved vigorously  and  twined.  So  that  this  plant 
produces  shoots  of  two  kinds.  With  Periploca  Grwea 
(Palm,  p.  43)  the  uppermost  shoots  alone  twine. 
Polygonum  convolvulus  twines  only  during  the  middle 
of  the  summer  (Palm,  p.  43,  94)  ;  and  plants  growing 
vigorously  in  the  autumn  show  no  inclination  to 
climb.     The  majority  of  Asclepiadaceae  are  twiners ; 


42  TWINING  PLANTS.  Chap.  I. 

but  Asdepias  nigra  only  "  in  fertiliori  solo  incipit 
scandere  subvolubili  caule  "  (Willdenow,  quoted  and 
confirmed  by  Palm,  j)-  41).  Asclepias  vineetoxieum  does 
not  regularly  twine,  but  occasionally  does  so  (Palm, 
p.  42;  Mohl,  p.  112)  when  growing  under  certain 
conditions.  So  it  is  with  two  species  of  Ceropepia,  as  I 
hear  from  Prof.  Harvey,  for  these  plants  in  their 
native  dry  South  African  home  generally  grow  erects 
from  6  inches  to  2  feet  in  height, — a  very  few  taller 
specimens  showing  some  inclination  to  curve ;  but 
when  cultivated  near  Dublin,  they  regularly  twined 
up  sticks  5  or  6  feet  in  height.  Most  Convolvulacese 
are  excellent  twiners ;  but  in  South  Africa  Ipomoea 
argyrxoides  almost  always  grows  erect  and  compact, 
from  about  12  to  18  inches  in  height,  one  specimen 
alone  in  Prof.  Harvey's  collection  showing  an  evident 
disposition  to  twine.  On  the  other  hand,  seedlings 
raised  near  Dublin  twined  up  sticks  above  8  feet  in 
height.  These  facts  are  remarkable;  for  there  can 
hardly  be  a  doubt  that  in  the  dryer  provinces  of 
South  Africa  these  plants  have  propagated  themselves 
for  thousands  of  generations  in  an  erect  condition  ; 
and  yet  they  have  retained  during  this  whole  period 
the  innate  power  of  spontaneously  revolving  and 
twining,  whenever  their  shoots  become  elongated 
under  proper  conditions  of  life.  Most  of  the  species 
of  Phaseolus  are  twiners  ;  but  certain  varieties  of  the 
P.  multijlorus  produce  (Leon,  p.  681)  two  kinds  of 
shoots,  some  upright  and  thick,  and  others  thin  and 
twining.    I  have  seen  striking  instances  of  this  curious 


Chap.  I.  TWINING  PLANTS.  43 

case  of  variability  in  "  Fulmer's  dwarf  forcing-bean," 
which  occasionally  produced  a  single  long  twining 
shoot. 

Solanum  dulcamara  is  one  of  the  feeblest  and 
poorest  of  twiners :  it  may  often  be  seen  growing  as 
an  upright  bush,  and  when  growing  in  the  midst  of 
a  thicket  merely  scrambles  up  between  the  branches 
without  twining;  but  when,  according  to  Dutrochet 
(tom.  xix.  p.  299),  it  grows  near  a  thin  and  flexible 
support,  such  as  the  stem  of  a  nettle,  it  twines  round 
it.  I  placed  sticks  round  several  plants,  and  vertically 
stretched  strings  close  to  others,  and  the  strings  alone 
were  ascended  by  twining.  The  stem  twines  in- 
differently to  the  right  or  left.  Some  others  pecies 
of  Solanum,  and  of  another  genus,  viz.  Sahroihamnus, 
belonging  to  the  same  family,  are  described  in  horti- 
cultural works  as  twining  plants,  but  they  seem  to 
possess  this  faculty  in  a  very  feeble  degree.  We  may 
suspect  that  the  species  of  these  two  genera  have  as 
yet  only  partially  acquired  the  habit  of  twining.  On 
the  other  hand  with  Tecoma  radicans,  a  member  of  a 
family  abounding  with  twiners  and  tendril-bearers,  but 
which  climbs,  like  the  ivy,  by  the  aid  of  rootlets,  we 
may  suspect  that  a  former  habit  of  twining  has  been 
lost,  for  the  stem  exhibited  slight  irregular  movements 
which  could  hardly  be  accounted  for  by  changes  in  the 
action  of  the  light.  There  is  no  difficulty  in  under- 
standing how  a  spirally  twining  plant  could  graduate 
into  a  simple  root-climber ;  for  the  young  internodes 
of  Bignonia  Tweedyana  and  of  Horja  carnosa  revolve 


44  TWINING  PLANTS.  Chap.  I. 

and  twine,  but  likewise  emit  rootlets  whicli  adhere  to 
any  fitting  surface,  so  that  the  loss  of  twining  would 
be  no  great  disadvantage  and  in  some  respects  an 
advantage  to  these  species,  as  they  would  then  ascend 
their  supports  in  a  more  direct  line.* 


*  Fritz  Miiller  has  published      climbing  plants  in  '  Bot.  Zeitung/ 
some  interesting  facts  and  views       1866,  pp.  57,  G5. 
on  the  structure  of  the  wood  of 


Chap.  IL  LEAF-CLIMBEES.  45 


CHAPTEE  II. 

Leaf-Climbees. 

Plants  ■which  climb  by  the  aid  of  spontaneously  revolving  and  sensitive 
petioles  —  Clematis  —  Tropxolum  — ■  Maurandia,  flower-peduncles 
moving  spontaneously  and  sensitive  to  a  touch — EhodocJdton — 
Lophospennum  —  internodes  sensitive  —  Solarium,  thickening  of 
the  clasped  petioles — Fumaria — Adlumia — Plants  which  climb  by 
the  aid  of  their  produced  midi'ibs —  Gloriosa  —  Flagellaria — 
Nepenthes — Summary  on  leaf-climbers. 

We  now  come  to  our  second  class  of  climbing  plants, 
namely,  those  which  ascend  by  the  aid  of  irritable  or 
'sensitire  organs.  For  convenience'  sake  the  plants 
in  this  class  have  been  grouped  under  two  sub-divisions, 
namely,  leaf-climbers,  or  those  which  retain  their 
leaves  in  a  functional  condition,  and  tendril-bearers. 
But  these  sub-divisions  graduate  into  each  other,  as 
we  shall  see  under  Corydalis  and  the  Gloriosa  lily. 

It  has  long  been  observed  that  several  j)lants  climb 
by  the  aid  of  their  leaves,  either  by  their  petioles  (foot- 
stalks) or  by  their  produced  midribs ;  but  beyond  this 
simple  fact  they  have  not  been  described.  Palm  and 
Mohl  class  these  plants  with  those  which  bear  tendrils  ; 
but  as  a  leaf  is  generally  a  defined  object,  the  present 
classification,  though  artificial,  has  at  least  some  advan- 
tages. Leaf-climbers  are,  moreover,  intermediate  in 
many  respects  between  twiners  and  tendril-bearers. 
Eight  species  of  Clematis  and  seven  of  Trojpeeolum  were 


46  LEAF-CLIMBEES.  Chap.  II. 

observed,  in  order  to  see  what  amount  of  difference 
in  the  manner  of  climbing  existed  within  the  same 
genus ;  and  the  differences  are  considerable. 

Clematis. — C.  glandulosa. — The  thin  upper  inter- 
nodes  revolve,  moving  against  the  course  of  the  sun, 
precisely  like  those  of  a  true  twiner,  at  an  average 
rate,  judging  from  three  revolutions,  of  3  hrs.  48  m. 
The  leading  shoot  immediately  twined  round  a  stick 
placed  near  it ;  but,  after  making  an  open  spire  of 
only  one  tm'u  and  a  half,  it  ascended  for  a  short  space 
straight,  and  then  reversed  its  course  and  wound  two 
turns  in  an  opposite  direction.  This  was  rendered 
possible  by  the  straight  piece  between  the  opposed 
spires  having  become  rigid.  The  simple,  broad,  ovate 
leaves  of  this  tropical  species,  with  their  short  thick 
petioles,  seem  but  ill-fitted  for  any  movement;  and 
whilst  twining  up  a  vertical  stick,  no  use  is  made  of 
them.  Nevertheless,  if  the  footstalk  of  a  young  leaf 
be  rubbed  with  a  thin  twig  a  few  times  on  any  side, 
it  will  in  the  course  of  a  few  hours  bend  to  that  side ; 
afterwards  becoming  straight  again.  The  under  side 
seemed  to  be  the  most  sensitive  ;  but  the  sensitiveness 
or  irritability  is  slight  compared  to  that  which  we 
shall  meet  with  in  some  of  the  following  species  ;  thus, 
a  loop  of  string,  weighing  1-64  grain  (106-2  mg.) 
and  hanging  for  some  days  on  a  young  footstalk, 
produced  a  scarcely  perceptible  effect.  A  sketch  is 
here  given  of  two  young  leaves  which  had  naturally 
caught  hold  of  two  thin  branches.  A  forked  twig  placed 
so  as  to  press  lightly  on  the  under  side  of  a  young 


Chap.  II. 


CLEMATIS. 


47 


footstalk  caused  it,  in  12  hrs.,  to  bend  greatly,  and 
ultimately  to  such  an  extent  that  the  leaf  passed  to 
the  opposite  side  of  the  stem ;  the  forked  stick  having 
been  remoyed,  the  leaf  slowly  recovered  its  former 
position. 

The  young  leaves  spontaneously  and  gradually  change 
their  position :  when  first  developed  the  petioles  are 
upturned  and  parallel  to  the  stem ;  they  then  slowly 
bend  downwards,  remaining  for  a  short  time  at  right 


Fig.  1. 
Clematis  glandulosa. 
With  two  young  leaves  clasping  two  twigs,  with  the  clasping  portions  thickened. 

angles  to  the  stem,  and  then  become  so  much  arched 
downwards  that  the  blade  of  the  leaf  points  to  the 
ground  with  its  tip  curled  inwards,  so  that  the  whole 
petiole  and  leaf  together  form  a  hook.  They  are  thus 
enabled  to  catch  hold  of  any  twig  with  which  they 
may  be  brought  into  contact  by  the  revolving  move- 
ment of  the  internodes.  If  this  does  not  happen,  they 
retain  their  hooked  shape  for  a  considerable  time,  and 
then  bending  upwards  reassume  their  original  upturned 


48  LEAF-CLIMBERS.  Chap.  II. 

position,  which  is  preserved  ever  afterwards.  The 
petioles  which  have  clasped  any  object  soon  become 
much  thickened  and  strengthened,  as  may  be  seen 
in  the  drawing. 

Clematis  montana. — The  long,  thin  petioles  of  the 
leaves,  wliilst  young,  are  sensitive,  and  when  lightly 
rubbed  bend  to  the  rubbed  side,  subsequently  becom- 
ing straight.  They  are  far  more  sensitive  than  the 
petioles  of  C.  glandulosa  ;  for  a  loop  of  thread  weighing 
a  quarter  of  a  grain  (16'2  mg.)  caused  them  to  bend ; 
a  loop  weighing  only  one-eighth  of  a  grain  (8-1  mg.) 
sometimes  acted  and  sometimes  did  not  act.  The 
sensitiveness  extends  from  the  blade  of  the  leaf  to 
the  stem.  I  may  here  state  that  I  ascertained  in 
all  cases  the  weights  of  the  string  and  thread  used 
by  carefully  weighing  50  inches  in  a  chemical  balance, 
and  then  cutting  off  measured  lengths.  The  main 
petiole  carries  three  leaflets ;  but  their  short,  sub- 
petioles  are  not  sensitive.  A  young,  inclined  shoot 
(the  plant  being  in  the  greenhouse)  made  a  large 
circle  opposed  to  the  course  of  the  sun  in  4  hrs.  20  m., 
but  the  next  day,  being  very  cold,  the  time  was 
5  hrs.  10  m.  A  stick  placed  near  a  revolving  stem  was 
soon  struck  by  the  petioles  which  stand  out  at  right 
angles,  and  the  revolving  movement  was  thus  arrested. 
The  petioles  then  began,  being  excited  by  the  contact, 
to  slowly  wind  round  the  stick.  When  the  stick  was 
thin,  a  petiole  sometimes  wound  twice  round  it. 
The  opposite  leaf  was  in  no  way  affected.  The  atti- 
tude  assumed   by   the    stem    after   the   petiole    had 


Chap.  II.  CLEMATIS.  49 

clasped  the  stick,  was  that  of  a  man  standing  by  a 
cohimn,  who  throws  his  arm  horizontally  round  it. 
With  respect  to  the  stem's  power  of  twining,  some 
remarks  will  be  made  under  C.  calijcina. 

Clematis  SieholcU. — A  shoot  made  three  revolutions 
against  the  sun  at  an  average  rate  of  3  hrs.  11m.  The 
power  of  twining  is  like  that  of  the  last  species.  Its 
leaves  are  nearly  similar  in  structure  and  in  function, 
excepting  that  the  sub-petioles  of  the  lateral  and 
terminal  leaflets  are  sensitive.  A  loop  of  thread, 
weighing  one-eighth  of  a  grain,  acted  on  the  main 
petiole,  but  not  until  two  or  three  days  had  elapsed. 
The  leaves  have  the  remarkable  habit  of  spon- 
t^ineously  revolving,  generally  in  vertical  ellipses,  in 
the  same  manner,  but  in  a  less  degree,  as  will  be 
described  under  C.  micro^hyUa. 

Clematis  calycina. — The  young  shoots  are  thin  and 
flexible :  one  revolved,  describing  a  broad  oval,  in 
5  hrs.  30  m.,  and  another  in  6  hrs.  12  m.  They  followed 
the  course  of  the  sun ;  but  the  course,  if  observed  long 
enough,  would  probably  be  found  to  vary  in  this  species, 
as  well  as  in  all  the  others  of  the  genus.  It  is  a  rather 
better  twiner  than  the  two  last  species  :  the  stem  some- 
times made  two  spiral  turns  round  a  thin  stick,  if  free 
from  twigs ;  it  then  ran  straight  up  for  a  space,  and 
reversing  its  course  took  one  or  two  turns  in  an 
opposite  direction.  This  reversal  of  the  spire  occurred 
in  all  the  foregoing  species.  The  leaves  are  so  small 
compared  with  those  of  most  of  the  other  species,  thai 
the  petioles  at  first  seem    ill-adapted   for   clasping. 


60  LEAF-CLIMBEES.  Chap.  II. 

Nevertheless,  the  main  service  of  the  revolving  move- 
ment is  to  bring  them  into  contact  with  surrounding 
objects,  which  are  slowly  but  securely  seized.  The 
young  petioles,  which  alone  are  sensitive,  have  their 
ends  bowed  a  little  downwards,  so  as  to  be  in  a  slight 
degree  hooked  ;  ultimately  the  whole  leaf,  if  it  catches 
nothing,  becomes  level.  I  gently  rubbed  with  a  thin 
twig  the  lower  surfaces  of  two  young  petioles  ;  and  in 
2  hrs.  30  m.  they  were  slightly  curved  downwards ;  in 
5  hrs.,  after  being  rubbed,  the  end  of  one  was  bent 
com23letely  back,  parallel  to  the  basal  portion  ;  in  4  hrs. 
subsequently  it  became  nearly  straight  again.  To 
show  how  sensitive  the  young  petioles  are,  I  may 
mention  that  I  just  touched  the  under  sides  of  two 
with  a  little  water-colour,  which  when  dry  formed 
an  excessively  thin  and  minute  crust;  but  this 
sufficed  in  24  hrs.  to  cause  both  to  bend  downwards. 
Whilst  the  plant  is  young,  each  leaf  consists  of  three 
divided  leaflets,  which  barely  have  distinct  petioles, 
and  these  are  not  sensitive ;  but  when  the  plant  is 
well  grown,  the  petioles  of  the  two  lateral  and  terminal 
leaflets  are  of  considerable  length,  and  become  sensi- 
tive so  as  to  be  capable  of  clasping  an  object  in  any 
direction. 

When  a  petiole  has  clasped  a  twig,  it  undergoes 
some  remarkable  changes,  which  may  be  observed 
with  the  other  species,  but  in  a  less  strongly  marked 
manner,  and  will  here  be  described  once  for  all.  The 
clasped  petiole  in  the  course  of  two  or  three  days 
swells  greatly,  and  ultimately  becomes  nearly  twice  as 


Chap.  II.  CLEMATIS.  51 

thick  as  the  opposite  one  which  has  clasped  nothing. 
When  thin  transverse  slices  of  the  two  are  placed 
under  the  microscope  their  difference  is  conspicuous : 
the  side  of  the  petiole  which  has  been  in  contact  with 
the  support,  is  formed  of  a  layer  of  colourless  cells  with 
their  longer  axes  directed  from  the  centre,  and  these 
are  very  much  larger  than  the  corresponding  cells 
in  the  opposite  or  unchanged  petiole ;  the  central 
cells,  also,  are  in  some  degree  enlarged,  and  the  whole 
is  much  indurated.  The  exterior  surface  generally 
becomes  bright  red.  But  a  far  greater  change  takes 
place  in  the  nature  of  the  tissues  than  that  which  is 
visible :  the  petiole  of  the  unclasped  leaf  is  flexible 
and  can  be  snapped  easily,  whereas  the  clasped  one 
acquires  an  extraordinary  degree  of  toughness  and 
rigidity,  so  that  considerable  force  is  required  to  pull 
it  into  pieces.  With  this  change,  great  durability  is 
probably  acquired ;  at  least  this  is  the  case  with  the 
clasped  petioles  of  Clematis  vitalba.  The  meaning  of 
these  changes  is  obvious,  namely,  that  the  petioles  may 
firmly  and  durably  support  the  stem. 

Clematis  microphylla,  var.  leptophylla. — The  long 
and  thin  internodes  of  this  Australian  species  revolve 
sometimes  in  one  direction  and  sometimes  in  an  op- 
posite one,  describing  long,  narrow,  irregular  ellipses 
or  large  circles.  Four  revolutions  were  completed 
within  five  minutes  of  the  same  av^'age  rate  of 
1  hr.  51  m. ;  so  that  this  species  moves  more  quickly 
than  the  others  of  the  genus.  The  shoots,  when  placed 
near  a  vertical  stick,  either  twine  round  it,  or  clasp  it 


52  LEAF-CLIMBERS.  Chap.  11. 

with  the  basal  portions  of  their  petioles.  The  leaves 
whilst  young  are  nearly  of  the  same  shape  as  those 
of  C.  viticella,  and  act  in  the  same  manner  like  a  hook, 
as  will  be  described  under  that  species.  But  the  leaflets 
are  more  divided,  and  each  segment  whilst  young 
terminates  in  a  hardish  point,  which  is  much  curved 
downwards  and  inwards  ;  so  that  the  whole  leaf  readily 
catches  hold  of  any  neighbouring  object.  The  petioles 
of  the  young  terminal  leaflets  are  acted  on  by  loops 
of  thread  weighing  ^th  and  even  j'gth  of  a  grain. 
The  basal  portion  of  the  main  petiole  is  much 
less  sensitive,  but  will  clasp  a  stick  against  which  it 
presses. 

The  leaves,  whilst  young,  are  continually  and  sponta- 
neously moving  slowly.  A  bell-glass  was  placed  over 
a  shoot  secured  to  a  stick,  and  the  movements  of  the 
leaves  were  traced  on  it  during  several  days.  A  very 
irregular  line  was  generally  formed ;  but  one  day,  in 
the  course  of  eight  hours  and  three  quarters,  the 
figure  clearly  represented  three  and  a  half  irregular 
ellipses,  the  most  perfect  one  of  which  was  completed 
in  2hrs.  35  m.  The  two  opposite  leaves  moved 
independently  of  each  other.  This  movement  of  the 
leaves  would  aid  that  of  the  internodes  in  bringing 
the  petioles  into  contact  with  surrounding  objects. 
I  discovered  this  movement  too  late  to  be  enabled  to 
observe  it  ii^  the  other  species ;,  but  from  analogy  I 
can  hardly  doubt  that  the  leaves  of  at  least  C.  viticella, 
C.  fiammula,  and  C.  vitalba  move  spontaneously  ;  and, 
judging  from  C.  Sieboldi,  this  probably  is  the  case  with 


CuAP.  II.  CLEMATIS.  53 

G.  montana  and  C.  calycina.  I  ascertained  that  the 
simple  leaves  of  C.  glandulosa  exhibited  no  sponta- 
neous revolving,  movement. 

Clematis  viticella,  var.  venosa. — -In  this  and  the  two 
following  species  the  power  of  spirally  twining  is 
completely  lost,  and  this  seems  due  to  the  lessened 
flexibility  of  the  internodes  and  to  the  interference 
caused  by  the  large  size  of  the  leaves.  But  the  re- 
volving movement,  though  restricted,  is  not  lost.  In 
our  present  species  a  young  internode,  placed  in  front 
of  a  window,  made  three  narrow  ellipses,  transversely 
to  the  direction  of  the  light,  at  an  average  rate  of 
2  hrs.  40  m.  When  placed  so  that  the  movements  were 
to  and  from  the  light,  the  rate  was  greatly  accelerated 
in  one  half  of  the  course,  and  retarded  in  the  other,  as 
with  twining  plants.  The  ellipses  were  small ;  the 
longer  diameter,  described  by  the  apex  of  a  shoot 
bearing  a  pair  of  not  expanded  leaves,  was  only  4| 
inches,  and  that  by  the  apex  of  the  penultimate  inter- 
node only  1\  inch.  At  the  most  favourable  period  of 
growth  each  leaf  would  hardly  be  carried  to  and  fro 
by  the  movement  of  the  internodes  more  than  two  or 
three  inches,  but,  as  above  stated,  it  is  probable  that 
the  leaves  themselves  move  spontaneously.  The  move- 
ment of  the  whole  shoot  by  the  wind  and  by  its  rapid 
growth,  would  probably  be  almost  equally  efficient  as 
these  spontaneous  movements,  in  bringing  the  petioles 
into  contact  with  surrounding  objects. 

The  leaves  are  of  large  size.  Each  bears  three  pairs 
of  lateral  leaflets  and  a  terminal  one,  all  supported  on 


54 


LEAF-CLIMBERS. 


CiiAP.  n. 


rather  long  sub-petioles.  The  main  petiole  bends  a 
little  angularly  downwards  at  each  point  where  a  pair 
of  leaflets  arises  (see  fig.  2),  and  the  petiole  of  the 
terminal  leaflet  is  bent  downwards  at  right  angles ; 
hence  the  whole  petiole,  with  its  rectangularly  bent 
extremity,  acts  as  a  hook.  This  hook,  the  lateral 
petioles  being  directed  a  little  upwards,  forms  an 
excellent   grappling  apparatus,  by  which  the  leaves 


Fig.  2. 
A  young  leaf  of  Clematis  viticella. 

readily  become  entangled  with  surrounding  objects. 
If  they  catch  nothing,  the  whole  petiole  ultimately 
grows  straight.  The  main  petiole,  the  sub-petioles, 
and  the  three  branches  into  which  each  basi-lateral 
sub-petiole  is  generally  subdivided,  are  all  sensitive. 
The  basal  portion  of  the  main  petiole,  between  the 
stem  and  the  first  pair  of  leaflets,  is  less  sensitive 
than  the  remainder;  it  will,  however,   clasp  a  stick 


Chap.  II.  CLEMATIS.  55 

with  which  it  is  left  in  contact.  The  inferior  surface 
of  the  rectangularly  bent  terminal  portion  (carrying 
the  terminal  leaflet),  which  forms  the  inner  side  of  the 
end  of  the  hook,  is  the  most  sensitive  part ;  and  this 
portion  is  manifestly  best  adapted  to  catch  a  distant 
support.  To  show  the  difference  in  sensibility,  I 
gently  placed  loops  of  string  of  the  same  weight  (in 
one  instance  weighing  only  '82  of  a  grain  or  53*14  mg.) 
on  the  several  lateral  sub-petioles  and  on  the  terminal 
one;  in  a  few  hours  the  latter  was  bent,  but  after 
24  hrs.  no  effect  was  produced  on  the  other  sub-petioles. 
Again,  a  terminal  sub-petiole  placed  in  contact  with  a 
thin  stick  became  sensibly  curved  in  45  m.,  and  in 
1  hr.  10  m.  moved  through  ninety  degrees ;  whilst 
a  lateral  sub-petiole  did  not  become  sensibly  curved 
until  3  hrs.  30  m.  had  elapsed.  In  all  cases,  if  the 
sticks  are  taken  away,  the  petioles  continue  to  move 
during  many  hours  afterwards ;  so  they  do  after  a 
slight  rubbing  ;  but  they  become  straight  again,  after 
about  a  day's  interval,  that  is  if  the  flexure  has  not 
been  very  great  or  long  continued. 

The  graduated  difference  in  the  extension  of  the 
sensitiveness  in  the  petioles  of  the  above-described 
species  deserves  notice.  In  C.  montana  it  is  confined 
to  the  main  petiole,  and  has  not  spread  to  the  sub- 
petioles  of  the  three  leaflets ;  so  it  is  with  young  plants 
of  G.  calycina,  but  in  older  plants  it  spreads  to  the 
three  sub-petioles.  In  C.  viticella  the  sensitiveness  has 
spread  to  the  petioles  of  the  seven  leaflets,  and  to  the 
subdivisions  of  the  basi-lateral  sub-petioles.     But  in 


56  LEAF-CLIMBERS.  Chap.  IL 

this  latter  species  it  has  diminished  in  the  basal  part 
of  the  main  petiole,  in  which  alone  it  resided  in  G. 
montana ;  whilst  it  has  increased  in  the  abruptly  bent 
terminal  portion. 

Clematis  jiammida. — The  rather  thick,  straight,  and 
stiff  shoots,  whilst  growing  vigorously  in  the  sj)ring, 
make  small  oval  revolutions,  following  the  sun  in  their 
course.  Four  were  made  at  an  average  rate  of  3  hrs. 
45  m.  The  longer  axis  of  the  oval,  described  by  the 
extreme  tip,  was  directed  at  right  angles  to  the  line 
joining  the  opposite  leaves ;  its  length  was  in  one  case 
only  If,  and  in  another  case  If  inch ;  so  that  the 
young  leaves  were  moved  a  very  short  distance.  The 
shoots  of  the  same  plant  observed  in  midsummer, 
when  growing  not  so  quickly,  did  not  revolve  at  all. 
I  cut  down  another  plant  in  the  early  summer,  so  that 
by  August  1st  it  had  formed  new  and  moderately 
vigorous  shoots;  these,  when  observed  under  a  bell- 
glass,  were  on  some  days  quite  stationary,  and  on 
other  days  moved  to  and  fro  only  about  the  eighth  of 
an  inch.  Consequently  the  revolving  power  is  much 
enfeebled  in  this  species,  and  under  unfavourable  cir- 
cumstances is  completely  lost.  The  shoot  must  depend 
for  coming  into  contact  with  surrounding  objects  on  the 
probable,  though  not  ascertained  spontaneous  move- 
ment of  the  leaves,  on  rapid  growth,  and  on  movement 
from  the  wind.  Hence,  perhaps,  it  is  that  the  petioles 
have  acquired  a  high  degree  of  sensitiveness  as  a  com- 
pensation for  the  little  power  of  movement  in  the  shoots. 

The  petioles  are  bowed  downwards,  and  have  the 


Chap.  II.  CLEMATIS.  57 

same  general  hook-like  form  as  in  C.  viiicella.  The 
medial  petiole  and  the  lateral  sub-petioles  are  sensitive, 
especially  the  much  bent  terminal  portion.  As  the 
sensitiveness  is  here  greater  than  in  any  other  species 
of  the  genus  observed  by  me,  and  is  in  itself  remark- 
able, I  will  give  fuller  details.  The  petioles,  when  so 
young  that  they  have  not  separated  from  one  another, 
are  not  sensitive ;  when  the  lamina  of  a  leaflet  has 
grown  to  a  quarter  of  an  inch  in  length  (that  is,  about 
one-sixth  of  its  full  size),  the  sensitiveness  is  highest ; 
but  at  this  period  the  petioles  are  relatively  much 
more  fully  developed  than  are  the  blades  of  the  leaves. 
Full-grown  petioles  are  not  in  the  least  sensitive.  A 
thin  stick  placed  so  as  to  press  lightly  against  a 
petiole,  having  a  leaflet  a  quarter  of  an  inch  in  length, 
caused  the  petiole  to  bend  in  3  hrs.  15  m.  In  another 
case  a  petiole  curled  completely  round  a  stick  in 
12  hrs.  These  petioles  were  left  curled  for  24  hrs.,  and 
the  sticks  were  then  removed ;  but  they  never 
straightened  themselves.  I  took  a  twig,  thinner  than 
the  petiole  itself,  and  with  it  lightly  rubbed  several 
petioles  four  times  up  and  down ;  these  in  1  hr.  45  m. 
became  slightly  curled ;  the  curvature  increased  during 
some  hours  and  then  began  to  decrease,  but  after  25  hrs. 
from  the  time  of  rubbing  a  vestige  of  the  curvature  re- 
mained. Some  other  petioles  similarly  rubbed  twice,  that 
is,  once  up  and  once  down,  became  perceptibly  curved 
in  about  2  hrs.  30  m.,  the  terminal  sub-petiole  moving 
more  than  the  lateral  sub-petioles;  they  all  became 
straight  again  in  between  12  hrs.  and  14  hrs.    Lastly,  a 


58  LEAF-CLIMBERS.  Chap.  IL 

length  of  about  one-eiglith  of  an  inch  of  a  sub-petiole, 
was  lightly  rubbed  with  the  same  twig  only  once ;  it 
became  slightly  curved  in  3  hrs.,  remaining  so  during 
11  hrs.,  but  by  the  next  morning  was  quite  straight. 

The  following  observations  are  more  precise.  After 
trying  heavier  pieces  of  string  and  thread,  I  placed  a 
loop  of  fine  string,  weighing  1*04  gr.  (67'4  mg.)  on  a 
terminal  sub-petiole :  in  6  hrs.  40  m.  a  curvature  could 
be  seen ;  in  24  hrs.  the  petiole  formed  an  open  ring  round 
the  string ;  in  48  hrs.  the  ring  had  almost  closed  on  the 
string,  and  in  72  hrs.  seized  it  so  firmly,  that  some 
force  was  necessary  for  its  withdrawal.  A  loop  weighing 
•52  of  a  grain  (o3*7  mg.)  caused  in  14  hrs.  a  lateral  sub- 
petiole  just  perceptibly  to  curve,  and  in  24  hrs.  it 
moved  through  ninety  degrees.  These  observations  were 
made  during  the  summer :  the  following  were  made 
in  the  spring,  when  the  petioles  apparently  are  more 
sensitive : — A  loop  of  thread,  weighing  one-eighth  of  a 
grain  (8'01  mg.),  produced  no  effect  on  the  lateral  sub- 
petioles,  but  placed  on  a  terminal  one,  caused  it,  after 
24  hrs.,  to  curve  moderately ;  the  curvature,  though  the 
loop  remained  suspended,  was  after  48  hrs.  diminished, 
but  never  disappeared ;  showing  that  the  petiole  had 
become  partially  accustomed  to  the  insufficient  stimulus. 
This  experiment  was  twice  repeated  with  nearly  the 
same  result.  Lastly,  a  loop  of  thread,  weighing  only 
one-sixteenth  of  a  grain  (4'05  mg.)  was  twice  gently 
placed  by  a  forceps  on  a  terminal  sub-petiole  (the 
plant  being,  of  course,  in  a  still  and  closed  room),  and 
this  weight  certainly  caused  a  flexure,  which  very 


Chap.  IL  CLEMATIS.  59 

slowly  increased  until  the  petiole  moved  tlirough  nearly 
ninety  degrees  :  beyond  this  it  did  not  move ;  nor  did 
the  petiole,  the  loop  remaining  suspended,  ever  become 
perfectly  straight  again. 

When  we  consider,  on  the  one  hand,  the  thickness 
and  stiffness  of  the  petioles,  and,  on  the  other  hand, 
the  thinness  and  softness  of  fine  cotton  thread,  and 
what  an  extremely  small  weight  one-sixteenth  of  a 
grain  (4-05  mg.)  is,  these  facts  are  remarkable.  But 
I  have  reason  to  believe  that  even  a  less  weight  excites 
curvature  when  pressing  over  a  broader  surface  than 
that  acted  on  by  a  thread.  Having  noticed  that 
the  end  of  a  susj)ended  string  which  accidentally 
touched  a  petiole,  caused  it  to  bend,  I  took  two 
pieces  of  thin  twine,-  10  inches  in  length  (weighing 
1'64  gr.),  and,  tying  them  to  a  stick,  let  them  hang  as 
nearly  perpendicularly  downwards  as  their  thinness 
and  flexuous  form,  after  being  stretched,  would  per- 
mit; I  then  quietly  placed  their  ends  so  as  just 
to  rest  on  two  petioles,  and  these  certainly  became 
curved  in  36  hrs.  One  of  the  ends  touched  the  angle 
between  a  terminal  and  lateral  sub-petiole,  and  it  was 
in  48  hours  caught  between  them  as  by  a  forceps.  In 
these  cases  the  pressure,  though  spread  over  a  wider 
surface  than  that  touched  by  the  cotton  thread,  must 
have  been  excessively  slight. 

Clematis  viiaTba. — The  plants  were  in  pots  and  not 
healthy,  so  that  I  dare  not  trust  my  observations,  which 
indicate  much  similarity  in  habits  with  C.jlammula.  I 
mention  this  species  only  because  I  have  seen  many 


60  LEAF-CLIMBEKS.  Chap.  II. 

proofs  that  the  petioles  in  a  state  of  nature  are  excited 
to  movement  by  very  slight  pressure.  For  instance, 
I  have  found  them  embracing  thin  withered  blades 
of  grass,  the  soft  young  leaves  of  a  maple,  and  the 
flower-peduncles  of  the  quaking-grass  or  Briza.  The 
latter  are  about  as  thick  as  the  hair  of  a  man's 
beard,  but  they  were  completely  surrounded  and  clasped. 
The  petioles  of  a  leaf,  so  young  that  none  of  the  leaflets 
were  expanded,  had  partially  seized  a  twig.  Those  of 
almost  all  the  old  leaves,  even  when  unattached  to  any 
object,  are  much  convoluted ;  but  this  is  owing  to  their 
having  come,  whilst  young,  into  contact  during  several 
hours  with  some  object  subsequently  removed.  With 
none  of  the  above-described  species,  cultivated  in  pots 
and  carefully  observed,  was  there  any  permanent 
bending  of  the  petioles  without  the  stimulus  of  contact. 
In  winter,  the  blades  of  the  leaves  of  C.  vitalha  drop 
off;  but  the  petioles  (as  was  observed  by  Mohl) 
remain  attached  to  the  branches,  sometimes  during 
two  seasons ;  and,  being  convoluted,  they  curiously 
resemble  true  tendrils,  such  as  those  j)ossessed  by 
the  allied  genus  Naravelia.  The  petioles  which  have 
clasped  some  object  become  much  more  stiff,  hard,  and 
polished  than  those  which  have  failed  in  this  their 
proper  function. 

Tkop^olum. — I  observed  T.  iricolorum,  T.  azureum, 
T.  pentaphyllum,  T.  peregrinum,  T.  elegans,  T.  tuberosum, 
and  a  dwarf  variety  of,  as  I  believe,  T.  minus. 

Tropxolum  tricolorum,  var.  grandijlorum. — The 
flexible  shoots,  which  first  rise  from  the  tubers,  are 


Ciiap.il  trop^olum,  •  61 

as  tliin  as  fine  twine.  One  such  shoot  revolved  in  a 
course  opposed  to  the  sun,  at  an  average  rate,  judging 
from  three  revolutions,  of  1  hr.  23  m, ;  but  no  doubt 
the  direction  of  the  revolving  movement  is  variable. 
When  the  plants  have  grown  tall  and  are  branched, 
all  the  many  lateral  shoots  revolve.  The  stem,  whilst 
young,  twines  regularly  round  a  thin  vertical  stick, 
and  in  one  case  I  counted  eight  spiral  turns  in  the 
same  direction ;  but  when  grown  older,  the  stem  often 
runs  straight  up  for  a  space,  and,  being  arrested  by 
the  clasping  petioles,  makes  one  or  two  spires  in  a 
reversed  direction.  Until  the  plant  grows  to  a  height 
of  two  or  three  feet,  requiring  about  a  month  from  the 
time  when  the  first  shoot  appears  above  ground,  no 
true  leaves  are  produced,  but,  in  their  place,  filaments 
coloured  like  the  stem.  The  extremities  of  these 
filaments  are  pointed,  a  little  flattened,  and  furrowed 
on  the  upper  surface.  They  never  become  developed 
into  leaves.  As  the  plant  grows  in  height  new  fila- 
ments are  produced  with  slightly  enlarged  tips  ;  then 
others,  bearing  on  each  side  of  the  enlarged  medial  tip 
a  rudimentary  segment  of  a  leaf ;  soon  other  segments 
appear,  and  at  last  a  perfect  leaf  is  formed,  with  seven 
deep  segments.  So  that  on  the  same  plant  we  may  see 
every  step,  from  tendril-like  clasping  filaments  to  perfect 
leaves  with  clasping  petioles.  After  the  plant  has  grown 
to  a  considerable  height,  and  is  secured  to  its  support 
by  the  petioles  of  the  true  leaves,  the  clasping  fila- 
ments on  the  lower  part  of  the  stem  wither  and  drop 
off;  so  that  they  perform  only  a  temporary  service. 


62  LEAF-CLIMBEKS.  Chap.  II. 

These  filaments  or  rudimentary  leaves,  as  well  as 
the  petioles  of  the  perfect  leaves,  whilst  young,  are 
highly  sensitive  on  all  sides  to  a  touch.  The  slightest 
rub  caused  them  to  curve  towards  the  rubbed  side  in 
about  three  minutes,  and  one  bent  itself  into  a  ring 
in  six  minutes ;  they  subsequently  became  straight. 
When,  however,  they  have  once  completely  clasped  a 
stick,  if  this  is  removed,  they  do  not  straighten  them- 
selves. The  most  remarkable  fact,  and  one  which  I  have 
observed  in  no  other  species  of  the  genus,  is  that  the 
filaments  and  the  petioles  of  the  young  leaves,  if  they 
catch  no  object,  after  standing  for  some  days  in  their 
original  position,  spontaneously  and  slowly  oscillate  a 
little  from  side  to  side,  and  then  move  towards  the 
stem  and  clasp  it.  They  likewise  often  become,  after 
a  time,  in  some  degree  spirally  contracted.  They 
therefore  fully  deserve  to  be  called  tendrils,  as  they 
are  used  for  climbing,  are  sensitive  to  a  touch,  move 
spontaneously,  and  ultimately  contract  into  a  spire, 
though  an  imperfect  one.  The  present  species  would 
have  been  classed  amongst  the  tendril-bearers,  had  not 
these  characters  been  confined  to  early  youth.  During 
maturity  it  is  a  true  leaf-climber. 

Trojjseolum  azureum. — An  upper  internode  made  four 
revolutions,  following  the  sun,  at  an  average  rate  of 
1  hr.  47  m.  The  stem  twined  spirally  round  a 
support  in  the  same  irregular  manner  as  that  of  the 
last  species.  Rudimentary  leaves  or  filaments  do  not 
exist.  The  petioles  of  the  young  leaves  are  very 
sensitive :  a  single  light  rub  with  a  twig  caused  one 


CuAP.  II.  TROPiEOLUM.  63 

to  move  perceptibly  in  5m,  and  another  in  6  m. 
The  former  became  bent  at  right  angles  in  15  min,,  and 
became  straight  again  in  between  5  hrs.  and  6  hrs.  A 
loop  of  thread  weighing  ^th  of  a  grain  caused  another 
petiole  to  curve. 

Trojpseolum  penta^liyllum. — This  species  has  not  the 
power  of  spirally  twining,  which  seems  due,  not  so  much 
to  a  want  of  flexibility  in  the  stem,  as  to  continual 
interference  from  the  clasping  petioles.  An  upper  inter- 
node  made  three  revolutions,  following  the  sun,  at  an 
average  rate  of  1  hr.  46  m.  The  main  purpose  of 
the  revolving  movement  in  all  the  species  of  Tro- 
jpseolum  manifestly  is  to  bring  the  petioles  into  contact 
with  some  supporting  object.  The  petiole  of  a  young 
leaf,  after  a  slight  rub,  became  curved  in  6  m. ;  another, 
on  a  cold  day,  in  20  m.,  and  others  in  from  8  m. 
to  10  m.  Their  curvature  usually  increased  greatly  in 
from  15  m.  to  20  m.,  and  they  became  straight  again  in 
between  5  hrs.  and  6  hrs.,  but  on  one  occasion  in  3  hrs. 
When  a  petiole  has  fairly  clasped  a  stick,  it  is  not  able, 
on  the  removal  of  the  stick,  to  straighten  itself.  The 
free  upper  part  of  one,  the  base  of  which  had  already 
clasped  a  stick,  still  retained  the  power  of  movement.  A 
loop  of  thread  weighing  ^th  of  a  grain  caused  a  petiole 
to  curve ;  but  the  stimulus  was  not  sufficient,  the  loop 
remaining  suspended,  to  cause  a  permanent  flexure.  If 
a  much  heavier  loop  be  placed  in  the  angle  between 
the  petiole  and  the  stem,  it  produces  no  effect ;  whereas 
we  have  seen  with  Clematis  montana  that  the  angle 
between  the  stem  and  petiole  is  sensitive. 


64  LEAF-CLIMBERS.  Chap.  II. 

Trojoseolum  pereffrinum. — The  first-formed  internodes 
of  a  young  plant  did  not  revolve,  resembling  in  this 
respect  those  of  a  twining  plant.  In  an  older  plant 
the  four  upper  internodes  made  three  irregular  re- 
volutions, in  a  course  opposed  to  the  sun,  at  an  average 
rate  of  1  hr.  48  min.  It  is  remarkable  that  the 
average  rate  of  revolution  (taken,  however,  but  from 
few  observations)  is  very  nearly  the  same  in  this  and 
the  two  last  species,  namely,  1  hr.  47  m.,  1  hr.  46  m., 
and  1  hr.  48  m.  The  j)i'esent  species  cannot  twine 
spirally,  which  seems  mainly  due  to  the  rigidity 
of  the  stem.  In  a  very  young  plant,  which  did  not 
revolve,  the  petioles  were  not  sensitive.  In  older 
plants  the  petioles  of  quite  young  leaves,  and  of  leaves 
as  much  as  an  inch  and  a  quarter  in  diameter,  are 
sensitive.  A  moderate  rub  caused  one  to  curve  in 
10  m.,  and  others  in  20  m.  They  became  straight 
again  in  between  5  lirs.  45  m.  and  8  hrs.  Petioles 
which  have  naturally  come  into  contact  with  a  stick, 
sometimes  take  two  turns  round  it.  After  they  have 
clasped  a  support,  they  become  rigid  and  hard.  They 
are  less  sensitive  to  a  weight  than  in  the  previous 
species ;  for  loops  of  string  weighing  '82  of  a  grain 
(53"14  mg.),  did  not  cause  any  curvature,  but  a  loop 
of  double  this  weight  (1'64  gr.)  acted. 

Tropseolum  elegans. — I  did  not  make  many  obser- 
vations on  this  species.  The  short  and  stiff  internodes 
revolve  irregularly,  describing  small  oval  figures. 
One  oval  was  completed  in  3  hrs.  A  young  petiole, 
when  rubbed,  became  slightly  curved  in  17m.;  and 


Chap.  II.  TROP^OLUM.  65 

afterwards  much  more  so.  It  was  nearly  straight  again 
in  8  hrs. 

Tropxolum  tuherosum. — On  a  phxnt  nine  inches  in 
height,  the  internodes  did  not  move  at  all ;  but  on 
an  older  plant  they  moved  irregularly  and  made 
small  imperfect  ovals.  These  movements  could  be 
detected  only  by  being  traced  on  a  bell-glass  placed 
over  the  plant.  Sometimes  the  shoots  stood  still  for 
hours;  during  some  days  they  moved  only  in  one 
direction  in  a  crooked  line ;  on  other  days  they  made 
small  irregular  spires  or  circles,  one  being  completed 
in  about  4  hrs.  The  extreme  points  reached  by  the 
apex  of  the  shoot  were  only  about  one  or  one  and  a  half 
inches  asunder ;  yet  this  slight  movement  brought  the 
petioles  into  contact  with  some  closely  surrounding 
twigs,  which  were  then  clasped.  With  the  lessened  power 
of  spontaneously  revolving,  compared  with  that  of  the 
previous  species,  the  sensitiveness  of  the  petioles  is 
also  diminished.  These,  w^hen  rubbed  a  few  times, 
did  not  become  curved  until  half  an  hour  had  elapsed ; 
the  curvature  increased  during  the  next  two  hours, 
and  then  very  slowly  decreased ;  so  that  they  some- 
times required  2-1  hrs.  to  become  straight  again. 
Extremely  young  leaves  have  active  petioles ;  one 
with  the  lamina  only  '15  of  an  inch  in  diameter,  that 
is,  about  a  twentieth  of  the  full  size,  firmly  clasped 
a  thin  twig.  But  leaves  grown  to  a  quarter  of  their 
full  size  can  likewise  act. 

Tropseolum  minus  (?). — The  internodes  of  a  variety 
named  "  dwarf  crimson  Nasturtium  "  did  not  revolve, 
4 


66  LEAF-CLIMBERS.  Chap.  II. 

but  moved  in  a  rather  irregular  course  during  the 
day  to  the  light,  and  from  the  light  at  night.  The 
petioles,  when  well  rubbed,  showed  no  power  of  curv- 
ing ;  nor  could  I  see  that  they  ever  clasped  any 
neighbouring  object.  We  have  seen  in  this  genus 
a  gradation  from  species  such  as  T.  tricolorum,  which 
have  extremely  sensitive  petioles,  and  internodes  which 
rapidly  revolve  and  spirally  twine  up  a  support,  to 
other  species  such  as  T.  elegans  and  T.  tuberosum,  the 
petioles  of  which  are  much  less  sensitive,  and  the  in- 
ternodes of  which  have  very  feeble  revolving  powers 
and  cannot  spirally  twine  round  a  support,  to  this  last 
species,  which  has  entirely  lost  or  never  acquired  these 
faculties.  From  the  general  character  of  the  genus, 
the  loss  of  power  seems  the  more  probable  alternative. 

In  the  present  species,  in  T.  elegans,  and  probably  in 
others,  the  flower-peduncle,  as  soon  as  the  seed-capsule 
begins  to  swell,  spontaneously  bends  abruptly  down- 
wards and  becomes  somewhat  convoluted.  If  a  stick 
stands  in  the  way,  it  is  to  a  certain  extent  clasped ;  but, 
as  far  as  I  have  been  able  to  observe,  this  clasping 
movement  is  independent  of  the  stimulus  from  contact. 

Antiekhine^. — In  this  tribe  (Lindley)  of  the 
Scrophulariaceae,  at  least  four  of  the  seven  included 
genera  have  leaf-climbing  species. 

Maurandia  Barclayana. — A  thin,  sliglitly  bowed 
shoot  made  two  revolutions,  following  the  sun,  each  in 
3  hrs.  17  min. ;  on  the  previous  day  this  same  shoot 
revolved  in  an  opposite  direction.  The  shoots  do  not 
twine  spirally,  but   climb  excellently  by  the  aid  of 


Chap.  II.  MAURANDIA.  67 

their  young  and  sensitive  petioles.  These  petioles, 
when  lightly  rubbed,  move  after  a  considerable  interval 
of  time,  and  subsequently  become  straight  again.  A 
loop  of  thread  weighing  ^th  of  a  grain  caused  them  to 
bend. 

Maurandia  sem]}erflorens. — This  freely  growing 
species  climbs  exactly  like  the  last,  by  the  aid  of  its 
sensitive  petioles.  A  young  internode  made  two 
circles,  each  in  1  hr.  46  min. ;  so  that  it  moved  almost 
twice  as  rapidly  as  the  last  species.  The  internodes 
are  not  in  the  least  sensitive  to  a  touch  or  pressure.  I 
mention  this  because  they  are  sensitive  in  a  closely  allied 
genus,  namely,  Lophospermum.  The  present  species  is 
unique  in  one  respect.  Mohl  asserts  (p.  45)  that  "  the 
flower-peduncles,  as  well  as  the  petioles,  wind  like 
tendrils ; "  but  he  classes  as  tendrils  such  objects 
as  the  spiral  flower-stalks  of  the  Vallisneria.  This 
remark,  and  the  fact  of  the  flower-peduncles  being 
decidedly  flexuous,  led  me  carefully  to  examine 
them.  They  never  act  as  true  tendrils ;  I  repeatedly 
placed  thin  sticks  in  contact  with  young  and  old 
peduncles,  and  I  allowed  nine  vigorous  plants  to 
grow  through  an  entangled  mass  of  branches  ;  but 
in  no  one  instance  did  they  bend  round  any  object. 
It  is  indeed  in  the  highest  degree  improbable  that 
this  should  occur,  for  they  are  generally  developed  on 
branches  which  have  already  securely  clasped  a 
support  by  the  petioles  of  their  leaves ;  and  when 
borne  on  a  free  depending  branch,  they  are  not 
produced   by  the   terminal   portion  of  the  internode 


68  LEAF-CLIMBERS.  Chap.  II. 

whicli  alone  has  the  power  of  revolving ;  so  that  they 
could  be  brought  only  by  accident  into  contact  with 
any  neighbouring  object.  Nevertheless  (and  this  is 
the  remarkable  fact)  the  flower-peduncles,  whilst 
young,  exhibit  feeble  revolving  powers,  and  are  slightly 
sensitive  to  a  touch.  Having  selected  some  stems 
which  had  firmly  clasped  a  stick  by  their  petioles, 
and  having  placed  a'  bell-glass  over  them,  I  traced 
the  movements  of  the  young  flower-peduncles.  The 
tracing  generally  formed  a  short  and  extremely  irre- 
gular line,  with  little  loops  in  its  course.  A  young 
peduncle  1^  inch  in  length  was  carefully  observed 
during  a  whole  day,  and  it  made  four  and  a  half 
narrow,  vertical,  irregular,  and  short  ellipses — each 
at  an  average  rate  of  about  2  hrs.  25  m.  An  ad- 
joining peduncle  described  ■  during  the  same  time 
similar,  though  fewer,  ellipses.  As  the  plant  had 
occupied  for  some  time  exactly  the  same  position, 
these  movements  could  not  be  attributed  to  any  change 
in  the  action  of  the  light.  Peduncles,  old  enough  for 
the  coloured  petals  to  be  just  visible,  do  not  move. 
With  respect  to  irritability,*  I  rubbed  two  young 
peduncles  (1^  inch  in  length)  a  few  times  very  lightly 
with  a  thin  twig  ;  one  was  rubbed  on  the  upper,  and 
the  other  on  the  lower  side,  and  they  became  in 
between  4  hrs.  and  5  hrs.  distinctly  bowed  towards 


*  It  appears  from  A.  Kerner's  -when  they  are  nibbed  or  shaken : 

interesting  observations,  that  tlie  Die     Schutzmittel    des     Pollens, 

flower-peduncles  of  a  large  number  1873,  p.  34. 
of  plants  are   irritable,  and  bend 


Chap.  II.  MAURANDIA.  G9 

these  sides ;  in  24  hrs.  subsequently,  they  straightened 
themselves.  Next  day  they  were  rubbed  on  the 
opposite  sides,  and  they  became  perceptibly  curved 
towards  these  sides.  Two  other  and  younger  pe- 
duncles (three-fourths  of  an  inch  in  length)  were 
lightly  rubbed  on  their  adjoining  sides,  and  they  be- 
came so  much  curved  towards  one  another,  that  the 
arcs  of  the  bows  stood  at  nearly  right  angles  to  their 
previous  direction ;  and  this  was  the  greatest  movement 
seen  by  me.  Subsequently  they  straightened  them- 
selves. Other  peduncles,  so  young  as  to  be  only 
three-tenths  of  an  inch  in  length,  became  curved  when 
rubbed.  On  the  other  hand,  peduncles  above  1^  inch 
in  length  required  to  be  rubbed  two  or  three  times, 
and  then  became  only  just  perceptibly  bowed.  Loops 
of  thread  suspended  on  the  peduncles  produced  no 
effect ;  loops  of  string,  however,  weighing  '82  and  1"64 
of  a  grain  sometimes  caused  a  slight  curvature ;  but 
they  were  never  closely  clasped,  as  were  the  far  lighter 
loops  of  thread  by  the  petioles. 

In  the  nine  vigorous  plants  observed  by  me,  it  is 
certain  that  neither  the  slight  spontaneous  movements 
nor  the  slight  sensitiveness  of  the  flower-peduncles 
aided  the  plants  in  climbing.  If  any  member  of  the 
ScrophulariaceoB  had  possessed  tendrils  produced  by 
the  modification  of  flower-peduncles,  I  should  have 
thought  that  this  species  of  Maurandia  had  perhaps 
retained  a  useless  or  rudimentary  vestige  of  a  former 
habit ;  but  this  A'iew  cannot  be  maintained.  We  may 
suspect  that,  owing   to   the  principle   of  correlation, 


70  LEAF-CLIMBERS.  Chap.  IL 

tlie  power  of  movement  has  been  transferred  to  the 
flower-peduncles  from  the  young  internodes,  and  sensi- 
tiveness from  the  young  petioles.  But  to  whatever 
cause  these  capacities  are  due,  the  case  is  interest- 
ing ;  for,  by  a  little  increase  in  power  through  natural 
selection,  they  might  easily  have  been  rendered  as 
useful  to  the  plant  in  climbing,  as  are  the  flower- 
peduncles  (hereafter  to  be  described)  of  Yitis  or 
Cardiospcrmum. 

Bhodochifon  voluhile. — A  long  flexible  shoot  swept  a 
large  circle,  following  the  sun,  in  5  hrs.  30  m. ;  and,  as 
the  day  became  warmer,  a  second  circle  was  completed 
in  4  hrs.  10  m.  The  shoots  sometimes  make  a  whole 
or  a  half  spire  round  a  vertical  stick,  they  then  run 
straight  up  for  a  space,  and  afterwards  turn  spirally  in 
an  opposite  direction.  The  petioles  of  very  young 
leaves  about  one-tenth  of  their  full  size,  are  highly 
sensitive,  and  bend  towards  the  side  which  is  touched ; 
but  they  do  not  move  quickly.  One  was  perceptibly 
curved  in  1  hr.  10  m.,  after  being  lightly  rubbed,  and 
became  considerably  curved  in  5  hrs.  40  m. ;  some 
others  were  scarcely  curved  in  5  hrs.  30  m.,  but  dis- 
tinctly so  in  6  hrs.  30  m.  A  curvature  was  perceptible 
in  one  petiole  in  between  4  hrs.  30  m.  and  5  hrs., 
after  the  suspension  of  a  little  loop  of  string.  A 
loop  of  fine  cotton  thread,  weighing  one  sixteenth  of  a 
grain  (4*05  mg.),  not  only  caused  a  petiole  slowly  to 
bend,  but  was  ultimately  so  firmly  clasped  that  it 
could  be  withdrawn  only  by  some  little  force.  The 
petioles,  when  coming  into  contact  with  a  stick,  take 


Chap.  II.  LOPHOSrERMUM.  71 

either  a  complete  or  half  a  turn  round  it,  and  ultimately 
increase  much  in  thickness.  They  do  not  possess  the 
power  of  spontaneously  revolving. 

Lophospermum  scandens,  xar.  ^urpureum. —  Some 
long,  moderately  thin  internodes  made  four  revolu- 
tions at  an  average  rate  of  3  hrs.  15  m.  The  course 
pursued  was  very  irregular,  namely,  an  extremely 
narrow  ellipse,  a  large  circle,  an  irregular  spire  or  a 
zigzag  line,  and  sometimes  the  apex  stood  still.  The 
young  petioles,  when  brought  by  the  revolving  move- 
ment into  contact  with  sticks,  clasped  them,  and  soon 
increased  considerably  in  thickness.  But  they  are  not 
quite  so  sensitive  to  a  weight  as  those  of  the  Bhodochi- 
ton,  for  loops  of  thread  weighing  one-eighth  of  a  grain 
did  not  always  cause  them  to  bend. 

This  plant  presents  a  case  not  observed  by  me  in 
any  other  leaf-climber  or  twiner,*  namely,  that  the 
young  internodes  of  the  stem  are  sensitive  to  a 
touch.  When  a  petiole  of  this  species  clasps  a  stick, 
it  draws  the  base  of  the  internode  against  it ;  and  then 
the  internode  itself  bends  towards  the  stick,  which  is 
caught  between  the  stem  and  the  petiole  as  by  a  pair 
of  pincers.  The  internode  afterwards  straightens  itself, 
excepting  the  part  in  actual  contact  with  the  stick. 
Young  internodes  alone  are  sensitive,  and  these  are 
sensitive  on  all  sides  along  their  whole  length.     I  made 


*  I  have  already  referred  to  the      Vries  (ibid.  p.  322)  is  sensitive  to 
case  of  the  twining  stem  of  Cus-      a  touch  like  a  tendril, 
cuta,   which,  according  to  H.  de 


72  LEAF-CLIMBERS.  Chap.  II. 

fifteen  trials  by  twice  or  thrice  lightly  rubbing  with  a 
thin  twig  several  internodes ;  and  in  about  2  hrs.,  but 
in  one  case  in  3  hrs.,  all  were  bent :  they  became 
straight  again  in  about  4  hrs.  afterwards.  An  inter- 
node,  which  was  rubbed  as  often  as  six  or  seven  times, 
became  just  perceptibly  cur"\;ed  in  1  hr.  15  m.,  and 
in  3  hrs.  the  curvature  increased  much ;  it  became 
straight  again  in  the  course  of  the  succeeding  night. 
I  rubbed  some  internodes  one  day  on  one  side,  and 
the  next  day  either  on  the  opposite  side  or  at  right 
angles  to  the  first  side  ;  and  the  curvature  was  always 
towards  the  rubbed  side. 

According  to  Palm  (p.  63),  the  petioles  of  Linaria 
cirrhosa  and,  to  a  limited  degree,  those  of  L.  elatine 
have  the  power  of  clasping  a  support. 

SoLANACEiE. — Solanum  jasminoides.Sovae  of  the 
species  in  this  large  genus  are  twiners  ;  but  the  present 
species  is  a  true  leaf-climber.  •  A  long,  nearly  upright 
shoot  made  four  revolutions,  moving  against  the  sun, 
very  regularly  at  an  average  rate  of  3  hrs,  26  m.  The 
shoots,  however,  sometimes  stood  still.  It  is  con- 
sidered a  greenhouse  plant ;  but  when  kept  there,  the 
petioles  took  several  days  to  clasp  a  stick :  in  the 
hothouse  a  stick  was  clasped  in  7  hrs.  In  the  green- 
house a  petiole  was  not  affected  by  a  loop  of  string, 
suspended  during  several  days  and  weighing  2^ 
grains  (163  mg.) ;  but  in  the  hothouse  one  was  made 
to  curve  by  a  loop  weighing  1-64  gr.  (106'27  mg.)  ;  and, 
on  the  removal  of  the  string,  it  became  straight  again. 
Another  petiole  was  not  at  all  acted  on  by  a   loop 


Chap,  n,  SOLANUM.  73 

weighing  only  "82  of  a  grain  (53' 14  mg.)  We  have 
seen  that  the  petioles  of  some  other  leaf-climbing  plants 
are  affected  by  one-thirteenth  of  this  latter  weight.  In 
this  species,  and  in  no  other  leaf-climber  seen  by  me, 
a  full-grown  leaf  is  capable  of  clasping  a  stick ;  but  in 
the  greenhouse  the  movement  was  so  extraordinarily 


Fig.  S. 
Solarium  jasminoides,  with  one  of  its  petioles  clasping  a  stick. 

slow  that  the  act  required  several  weeks  ;  on  each 
succeeding  week  it  was  clear  that  the  petiole  had 
become  more  and  more  curved,  until  at  last  it  firmly 
clasped  the  stick. 

The  flexible  petiole  of  a  half  or  a  quarter  grown 
leaf  which  has  clasped  an  object  for  three  or  four 
days  increases  much  in  thickness,  and  after  several 
weeks  becomes  so  wonderfully  hard  and  rigid  that  it 


74  LEAF-CLIMBERS.  Chap.  II. 

can  hardly  be  removed  from  its  support.  On  com- 
paring a  thin  transverse  slice  of  such  a  petiole  with  one 
from  an  older  leaf  growing  close  beneath,  which  had  not 
clasped  anything,  its  diameter  was  found  to-  be  fully 
doubled,  and  its  structiu-e  greatly  changed.  In  two 
other  petioles  similarly  compared,  and  here  represented, 
the  increase  in  diameter  was  not  quite  so  great.  In 
the  section  of  the  petiole  in  its  ordinary  state  (A), 
we   see    a    semilunar    band    of    cellular    tissue    (not 


Fig.  4. 
Solanum  jasminoides. 

A.  Section  of  a  petiole  In  its  ordinary  state. 

B.  Section  of  a  petiole  some  weeks  after  it  had  clasped  a  stick,  as  shown  in  fig  3. 

well  shown  in  the  woodcut)  differing  slightly  in 
aj)pearance  from  that  outside  it,  and  including  three 
closely  approximate  groups  of  dark  vessels.  Near 
the  upper  surface  of  the  petiole,  beneath  two  exterior 
ridges,  there  are  two  other  small  circular  groups  of 
vessels.  In  the  section  of  the  petiole  (B)  which  had 
clasped  during  several  weeks  a  stick,  the  two  exterior 
ridges  have  become  much  less  prominent,  and  the  two 
groups  of  woody  vessels  beneath  them  much  increased 
in  diameter.  The  semilunar  band  has  been  converted 
into    a   complete   ring   of    very  hard,   white,   woody 


Chap.  II.  SOLANUM.  75 

tissue,  with  lines  radiating  from  the  centre.  The 
three  groups  of  vessels,  which,  though  near  together, 
were  before  distinct,  are  now  completely  blended. 
The  upper  part  of  this  ring  of  woody  vessels,  formed 
by  the  prolongation  of  the  horns  of  the  original  semi- 
lunar band,  is  narrower  than  the  lower  part,  and 
slightly  less  compact.  This  petiole  after  clasping  the 
stick  had  actually  become  thicker  than  the  stem 
from  which  it  arose ;  and  this  was  chiefly  due  to  the 
increased  thickness  of  the  ring  of  wood.  This  ring 
presented,  both  in  a  transverse  and  longitudinal 
section,  a  closely  similar  structure  to  that  of  the 
stem.  It  is  a  singular  morphological  fact  that 
the  petiole  should  thus  acquire  a  structure  almost 
identically  the  same  with  that  of  the  axis ;  and  it 
is  a  still  more  singular  physiological  fact  that  so  great 
a  change  should  have  been  induced  by  the  mere  act 
of  clasping  a  support.* 

FuMAEiACE^. — Famaria  officinalis. — It  could  not 
have  been  anticipated  that  so  lowly  a  plant  as  this 
Fumaria  should  have  been  a  climber.  It  climbs  by 
the  aid  of  the  main  and  lateral  petioles  of  its  com- 
pound leaves ;  and  even  the  much-flattened  terminal 


*  Dr.  Maxwell  Masters  informs  surfaces.    In  accordance  with  this 

me   that  in    almost   all    petioles  statement,    it   may    be   observed 

which   are  cylindrical,    such    as  that   the  enlarged    and    clasped 

those  bearing  peltate  leaves,  the  petiole  of  the  Solanum,  with  its 

woody  vessels  form  a  closed  ring ;  closed  ring  of  woody  vessels,  has 

semilunar  bands  of  vessels  being  become  more  cylindrical  tlian  it 

confined  to   petioles    which    are  was    in    its  original    unclasped 

channelled      along    their    upper  condition. 


76  LEAF-CLIMBEES.  Chap.  II. 

portion  of  the  petiole  can  seize  a  support.  I  have 
seen  a  substance  as  soft  as  a  witliered  bhxcle  of  grass 
caught.  Petioles  which  have  clasped  any  object 
ultimately  become  rather  thicker  and  more  cylindri- 
cal. On  lightly  rubbing  several  petioles  with  a  twig, 
they  became  perceptibly  curved  in  1  hr.  15  m.,  and 
subsequently  straightened  themselves.  A  stick  gently 
placed  in  the  angle  between  two  sub-petioles  excited 
them  to  move,  and  was  almost  clasped  in  9  hrs.  A 
loop  of  thread,  weighing  one-eighth  of  a  grain,  caused, 
after  12  hrs.  and  before  20  hrs.  had  elapsed,  a  consider- 
able curvature  ;  but  it  was  never  fairly  clasped  by  the 
petiole.  The  young  internodes  are  in  continual  move- 
ment, which  is  considerable  in  extent,  but  very  irregu- 
lar ;  a  zigzag  line,  or  a  spire  crossing  itself,  or  a  figure 
of  8  being  formed.  The  course  during  12  hrs.,  when 
traced  on  a  bell-glass,  apparently  represented  about 
four  ellipses.  The  leaves  themselves  likewise  move 
spontaneously,  the  main  petioles  curving  themselves 
in  accordance  with  the  movements  of  the  internodes ; 
so  that  when  the  latter  moved  to  one  side,  the  petioles 
moved  to  the  same  side,  then,  becoming  straight, 
reversed  their  curvatiu'e.  The  petioles,  however, 
do  not  move  over  a  wide  space,  as  could  be  seen  when 
a  shoot  was  securely  tied  to  a  stick.  The  leaf  in  this 
case  followed  an  irregular  course,  like  that  made  by 
the  internodes. 

Adlumia  cirrhosa. — I  raised  some  plants  late  in  the 
summer;  they  formed  very  fine  leaves,  but  threw 
up  110  central  stem.     The  first-formed  leaves  were  not 


Chap.  II.  ADLUMIA.  77 

sensitive ;  some  of  the  later  ones  were  so,  but  only 
towards  their  extremities,  which  were  thus  enabled  to 
clasp  sticks.  This  could  be  of  no  service  to  the  plant, 
as  these  leaves  rose  from  the  ground ;  but  it  showed 
what  the  future  character  of  the  plant  would  have 
been,  had  it  grown  tall  enough  to  climb.  The  tip 
of  one  of  these  basal  leaves,  whilst  young,  described 
in  1  hr.  36  m.  a  narrow  ellipse,  open  at  one  end,  and 
exactly  three  inches  in  length ;  a  second  ellipse  was 
broader,  more  irregular,  and  shorter,  viz.,  only  2^ 
inches  in  length,  and  was  completed  in  2hrs,  2  m. 
From  the  analogy  of  Fumaria  and  Corydalis,  I  have  no 
doubt  that  the  internodes  of  Adlumia  have  the  power 
of  revolving. 

Corydalis  claviculata. — This  plant  is  interesting 
from  being  in  a  condition  so  exactly  intermediate 
between  a  leaf-climber  and  a  tendril-bearer,  that  it 
might  have  been  described  under  either  head;  but, 
for  reasons  hereafter  assigned,  it  has  been  classed 
amongst  tendril-bearers. 

Besides  the  plants  already  described,  Bignonia 
unguis  and  its  close  allies,  though  aided  by  tendrils, 
have  clasping  petioles.  According  to  Mohl  (p.  40), 
Coccidus  Jajjonicus  (one  of  the  Menispermaceai)  and  a 
fern,  the  Ophioglossum  Japonicwn  (p.  39),  climb  by 
their  leaf-stalks. 

We  now  come  to  a  small  section  of  plants  which 
climb  by  means  of  the  produced  midribs  or  tips  of 
their  leaves. 


78  LEAF-CLIMBERS,  Chap.  IL 

LiLiACE^. — Gloriosa  PlarUii.— The  stem  of  a  half- 
grown  plant  continually  moved,  generally  describ- 
ing an  irregular  spire,  but  sometimes  oval  figures 
with  the  longer  axes  directed  in  different  lines.  It 
either  followed  the  sun,  or  moved  in  an  oj)posite 
course,  and  sometimes  stood  still  before  reversing  its 
direction.  One  oval  was  completed  in  3  hrs.  40  m. ;  of 
two  horseshoe-shaped  figures,  one  was  completed  in 
4  hrs.  35  m.  and  the  other  in  3  hrs.  The  shoots,  in  their 
movements,  reached  points  between  four  and  five 
inches  asunder.  The  young  leaves,  when  first  de- 
veloped, stand  up  nearly  vertically ;  but  by  the 
growth  of  the  axis,  and  by  the  spontaneous  bending 
down  of  the  terminal  half  of  the  leaf,  they  soon 
become  much  inclined,  and  ultimately  horizontal. 
The  end  of  the  leaf  forms  a  narrow,  ribbon-like, 
thickened  projection,  which  at  first  is  nearly  straight, 
but  by  the  time  the  leaf  gets  into  an  inclined  position, 
the  end  bends  downwards  into  a  well-formed  hook. 
This  hook  is  now  strong  and  rigid  enough  to  catch 
any  object,  and,  when  caught,  to  anchor  the  plant  and 
stop  the  revolving  movement.  Its  inner  surface  is 
sensitive,  but  not  in  nearly  so  high  a  degree  as  that 
of  the  many  before-described  petioles;  for  a  loop  of 
string,  weighing  1"64  grain,  produced  no  effect. 
When  the  hook  has  caught  a  thin  twig  or  even  a 
rigid  fibre,  the  point  may  be  perceived  in  from  1  hr.  to 
3 hrs.  to  have  curled  a  little  inwards;  and,  under 
favourable  circumstances,  it  curls  round  and  perma- 
nently  seizes  an   object  in  from   8   hrs.    to    10   hrs. 


Chap.  II.  GLORIOSA.  79 

The  liook  when  first  formed,  before  the  leaf  has 
bent  downwards,  is  but  little  sensitive.  If  it  catches 
hold  of  nothing,  it  remains  open  and  sensitive  for 
a  long  time ;  ultimately  the  extremity  spontaneously 
and  slowly  curls  inwards,  and  makes  a  button-like, 
flat,  spiral  coil  at  the  end  of  the  leaf.  One  leaf 
was  watched,  and  the  hook  remained  open  for  thirty- 
three  days ;  but  during  the  last  week  the  tip  had 
curled  so  much  inwards  that  only  a  very  thin  twig 
could  have  been  inserted  within  it.  As  soon  as  the 
tip  has  curled  so  much  inwards  that  the  hook  is  con- 
verted into  a  ring,  its  sensibility  is  lost ;  but  as  long  as 
it  remains  open  some  sensibility  is  retained. 

Whilst  the  plant  was  only  about  six  inches  in 
height,  the  leaves,  four  or  five  in  number,  were 
broader  than  those  subsequently  produced ;  their  soft 
and  but  little  -  attenuated  tips  were  not  sensitive, 
and  did  not  form  hooks ;  nor  did  the  stem  then  revolve. 
At  this  early  period  of  growth,  the  plant  can  support 
itself;  its  climbing  powers  are  not  required,  and 
consequently  are  not  developed.  So'  again,  the  leaves 
on  the  summit  of  a  full-grown  flowering  plant,  which 
would  not  require  to  climb  any  higher,  were  not  sensi- 
tive and  could  not  clasp  a  stick.  We  thus  see  how 
perfect  is  the  economy  of  nature. 

CoMMELYNACE^. — Flagellaria  Inclica. — From  dried 
specimens  it  is  manifest  that  this  plant  climbs  exactly 
like  the  Gloriosa.  A  young  plant  12  inches  in  height, 
and  bearing  fifteen  leaves,  had  not  a  single  leaf  as  yet 
produced  into  a  hook  or  tendril-like  filament ;  nor  did 


80  LEAF-CLIMBERS.  ChaP,  U. 

the  stem  revolve.  Hence  this  plant  acquires  its 
climbing  powers  later  in  life  than  does  -the  Gloriosa 
lily.  According  to  Mohl  (p.  41),  Uvularia  (Melan- 
thacese)  also  climbs  like  Gloriosa. 

These  three  last-named  genera  are  Monocotyledons ; 
but  there  is  one  Dicotyledon,  namely  Nepenthes,  which 
is  ranked  by  Mohl  (p.  41)  amongst  tendril-bearers; 
and  I  hear  from  Dr.  Hooker  that  most  of  the  species 
climb  well  at  Kew.  This  is  effected  by  the  stalk  or 
midrib  between  the  leaf  and  the  pitcher  coiling  round 
any  support.  The  twisted  part  becomes  thicker ;  but 
I  observed  in  Mr.  Veitch's  hothouse  that  the  stalk 
often  takes  a  turn  when  not  in  contact  with  any 
object,  and  that  this  twisted  part  is  likewise  thickened. 
Two  vigorous  young  plants  of  N.  Ixvis  and  N.  distilla- 
toria,  in  my  hothouse,  whilst  less  than  a  foot  in 
height,  showed  no  sensitiveness  in  their  leaves,  and 
had  no  power  of  climbing.  But  when  N.  Imvis  had 
grown  to  a  height  of  16  inches,  there  were  signs  of 
these  powers.  The  young  leaves  when  first  formed 
stand  upright,  but  soon  become  inclined ;  at  this 
period  they  terminate  in  a  stalk  or  filament,  with  the 
pitcher  at  the  extremity  hardly  at  all  developed. 
The  leaves  now  exhibited  slight  spontaneous  move- 
ments ;  and  when  the  terminal  filaments  came  into 
contact  with  a  stick,  they  slowly  bent  round  and 
firmly  seized  it.  But  owing  to  the  subsequent 
growth  of  the  leaf,  this  filament  became  after  a  time 
quite  slack,  though  still  remaining  firmly  coiled 
round  the  stick.     Hence  it  would  appear    that   the 


Chap.  II.  LEAF-CLIMBERS.  81 

chief  use  of  the  coiling,  at  least  whilst  the  plant  is 
young,  is  to  support  the  pitcher  with  its  load  of 
secreted  fluid. 

Summarij  on  Leaf-cUmhers. — Plants  belonging  to 
eight  families  are  known  to  have  clasping  petioles,  and 
plants  belonging  to  four  families  climb  by  the  tips  of 
their  leaves.  In  all  the  species  observed  by  me, 
with  one  exception,  the  young  internodes  revolve  more 
or  less  regularly,  in  some  cases  as  regularly  as  those 
of  a  twining  plant.  They  revolve  at  various  rates, 
in  most  cases  rather  rapidly.  Some  few  can  ascend 
by  spirally  twining  round  a  support.  Differently  from 
most  twiners,  there  is  a  strong  tendency  in  the  same 
shoot  to  revolve  first  in  one  and  then  in  an  opposite 
direction.  The  object  gained  by  the  revolving  move- 
ment is  to  bring  the  petioles  or  the  tips  of  the  leaves 
into  contact  with  surrounding  objects ;  and  without  this 
aid  the  plant  would  be  much  less  successful  in  climb- 
ing. With  rare  exceptions,  the  petioles  are  sensitive 
only  whilst  young.  They  are  sensitive  on  all  sides, 
but  in  different  degrees  in  different  plants ;  and  in 
some  species  of  Clematis  the  several  parts  of  the  same 
petiole  differ  much  in  sensitiveness.  The  hooked 
tips  of  the  leaves  of  the  Gloriosa  are  sensitive  only  on 
their  inner  or  inferior  surfaces.  The  petioles  are  sen- 
sitive to  a  touch  and  to  excessively  slight  continued 
pressure,  even  from  a  loop  of  soft  thread  weighing 
only  the  one-sixteenth  of  a  grain  (4*05  mg.) ;  and 
there  is  reason  to  believe  that  the  rather  thick  and 


82  LEAF-CLIMBERS.  Chap.  II. 

stiff  petioles  of  Clematis  flammula  are  sensitive  to  even 
much  less  weiglit  if  spread  over  a  wide  surface.  The 
petioles  always  bend  towards  the  side  which  is  pressed 
or  touched,  at  different  rates  in  different  species, 
sometimes  within  a  few  minutes,  but  generally  after 
a  much  longer  period.  After  temporary  contact  with 
any  object,  the  petiole  continues  to  bend  for  a  con- 
siderable time ;  afterwards  it  slowly  becomes  straight 
again,  and  can  then  re-act.  A  petiole  excited  by  an 
extremely  slight  weight  sometimes  bends  a  little,  and 
then  becomes  accustomed  to  the  stimulus,  and  either 
bends  no  more  or  becomes  straight  again,  the  weight 
still  remaining  suspended.  Petioles  which  have  clasped 
an  object  for  some  little  time  cannot  recover  their 
original  position.  After  remaining  clasped  for  two  or 
three  days,  they  generally  increase  much  in  thickness 
either  throughout  their  whole  diameter  or  on  one  side 
alone ;  they  subsequently  become  stronger  and  more 
woody,  sometimes  to  a  wonderful  degree  ;  and  in  some 
cases  they  acquire  an  internal  structur.e  like  that  of  the 
stem  or  axis. 

The  young  internodes  of  the  LopJwspermum  as  well 
as  the  petioles  are  sensitive  to  a  touch,  and  by  their 
combined  movement  seize  an  object.  The  flower- 
peduncles  of  the  Maurandia  semperjlorens  revolve 
spontaneously  and  are  sensitive  to  a  touch,  yet  are  not 
used  ^  for  climbing.  The  leaves  of  at  least  two,  and 
probably  of  most,  of  the  species  of  Clematis,  of  Fumaria 
and  Adlumia,  spontaneously  curve  from  side  to  side, 
like  the  internodes,  and  are  thus  better  adapted  to 


CuAP.  II.  LEAF-CLIMBERS.  83 

seize  distant  objects.  The  petioles  of  the  perfect 
leaves  of  Tro^molum  tricolorum,  as  well  as  the  tendril- 
like filaments  of  the  plants  whilst  young,  ultimately 
move  towards  the  stem  or  the  supporting  stick,  which 
they  then  clasp.  These  petioles  and  filaments  also 
show  some  tendency  to  contract  spirally.  The  tips  of 
the  uncaught  leaves  of  the  Gloriosa,  as  they  grow  old, 
contract  into  a  flat  spire  or  helix.  These  several  facts 
are  interesting  in  relation  to  true  tendrils. 

With  leaf  climbers,  as  Avith  twining  plants,  the  first 
internodes  which  rise  from  the  ground  do  not,  at  least 
in  the  cases  observed  by  me,  spontaneously  revolve ; 
nor  are  the  petioles  or  tips  of  the  first-formed  leaves 
sensitive.  In  certain  species  of  Clematis,  the  large  size 
of  the  leaves,  together  with  their  habit  of  revolving, 
and  the  extreme  sensitiveness  of  their  petioles,  appear 
to  render  the  revolving  movement  of  the  internodes 
superfluous ;  and  this  latter  power  has  consequently 
become  much  enfeebled.  In  certain  species  of  Tro- 
IJseolum,  both  the  spontaneous  movements  of  the  inter- 
nodes and  the  sensitiveness  of  the  petioles  have  become 
much  enfeebled,  and  in  one  species  have  been  com- 
pletely lost. 


CHAPTEE   III. 

Tendkil-Beaeeks. 

Nature  of  tendiils — Bignoniace^,  various  species  of,  and  theii-  different 
modes  of  climbing — Tendrils  'wliicli  avoid  the  light  and  creep 
into  crevices — Development  of  adhesive  discs — Excellent  adapta- 
tions for  seizing  different  kinds  of  supports — Polemoxiace^ — 
Cdbxa  scandens,  much  branched  and  hooked  tendrils,  their  manner 
of  action — LEcriiixos^ — Composite — Sjiilace^— /Sm/Zna;  aspera, 
its  inefficient  tendrils — Fumariace^ — CorydaUs  claviculata,  its 
state  intermediate  between  that  of  a  leaf-climber  and  a  tendi-il- 
bearer. 

By  tendrils  I  mean  filamentary  organs,  sensitive  to 
contact  and  used  exclusively  for  climbing.  By  tbis 
definition,  spines,  hooks  and  rootlets,  all  of  which  are 
used  for  climbing,  are  excluded.  True  tendrils  are 
formed  by  the  modification  of  leaves  with  their  petioles, 
of  flower-peduncles,  branches,*  and  perhaps  stipules. 


*  Never  having  had  the  oppor-  (1.)  Plants  supporting  themselves 

tunity     of     examining     tendrils  simijly  by  theu- branches  stretched 

produced  by  the  modification  of  out  at  right  angles — for  example, 

branches,  I  spoke  doubtfully  about  Chiococca.     (2.)  Plants  clasping  a 

them    in    this    essay  wheu    ori-  support    with    their    unmodified 

ginally     published.      But     since  branches,     as    -with    Securidaca. 

then  Fritz  Midler  has  described  (3.)  Plants  climbing  by  the   ex- 

(Journal  of  Linn.  Soc.  vol.  is.  p.  tremities  of  their  branches  which 

3-44)  many  striking  cases  in  South  appear  like  tendrils,  as  is  the  case 

Brazil.       In   speaking   of    plants  according     to     Endlicher     with 

which  climb  by  the  aid  of  their  Helinus.     (4.)  Plants  with  the  r 

branches,  more    or  less  modified,  branches     much     modified     and 

he  states  that  the  following  stages  temporarily  converted    into   ten- 

of  development    can   be    traced :  drils,  but  which  may  be  again 


Chap.  IU. 


TEN  DRIL-BEAEEES. 


85 


Mohl,  who  includes  under  the  name  of  tendrils  various 
organs  having  a  similar  external  appearance,  classes 
them  according  to  their  homological  nature,  as  being 
modified  leaves,  flower-peduncles,  &c.  This  would  be 
an  excellent  scheme  ;  but  I  observe  that  botanists  are 
by  no  means  unanimous  on  the  homological  nature  of 
certain  tendrils.  Consequently  I  will  describe  tendril- 
bearing  plants  by  natural  families,  following  Lindley's 
classification ;  and  this  will  in  most  cases  keep  those  of 
the  same  nature  together.  The  species  to  be  described 
belong  to  ten  families,  and  will  be  given  in  the 
following  order  : — Bignoniacex,  Folemoniacese,  Legu- 
minosse,  ComjMsitx,  Smilacess,  Fumariace^,  CucurMtaceie, 
Vitacese,  Sapmdacem,  Passijloraeeas* 


transformed  into  branches,  as  with 
certain  Papilionaceous  plants. 
(5.)  Plants  with  their  branches 
forming  true  tendrils,  and  used 
exclusively  for  climbing — as  with 
Strychnos  and  Cauloiretus.  Even 
the  unmodiiied  branches  become 
much  thickened  when  they  wind 
round  a  support.  I  may  add  that 
Mr.  Thwaites  sent  me  from  Ceylon 
a  specimen  of  an  Acacia  which 
had  climbed  up  the  trunk  of  a 
rather  large  tree,  by  the  aid  of 
tendril-like,  curved  or  convoluted 
branchlets,  arrested  in  their 
growth  and  furnished  with  sharp 
recurved  hooks. 

*  As  far  as  I  can  make  out,  the 
history  of  our  knowledge  of 
tendrils  is  as  follows: — "We  have 
seen  that  Palm  and  von  Mohl 
observed  about  the  same  time  the 


singular  phenomenon  of  the  spon- 
taneous revolving  movement  of 
twining-plants.  Palm  (p.  58),  I 
presume,  observed  likewise  the 
revolving  movement  of  tendrils; 
but  I  do  not  feel  snre  of  this,  for 
he  says  very  little  on  the  subject. 
Dutrochet  fully  described  this 
movement  of  the  tendril  in  the 
common  pea.  Mohl  first  discover- 
ed that  tendrils  are  sensitive  to 
contact ;  but  from  some  cause, 
probably  from  observing  too  old 
tendrils,  he  was  not  aware  how 
sensitive  they  were,  and  thought 
that  prolonged  pressnre  was  neces- 
sary to  excite  their  movement. 
Professor  Asa  Gray,  in  a  paper 
ab-eady  quoted,  first  noticed  the 
extreme  sensitiveness  and  rapidity 
of  the  movements  of  the  tendrils 
of  certain  Cucurbitaceous  plants. 


86 


TENDKIL-BEAEEES. 


Chap.  III. 


BiGNONiACE^. — This  family  contains  many  tendril- 
bearers,  some  twiners,  and  some  root-climbers.  The 
tendrils  always  consist  of  modified  leaves.  Nine  species 
of  Bignonia,  selected  by  hazard,  are  here  described, 
in  order  to  show  what  diversity  of  structure  and 
action  there  may  be  within  the  same  genus,  and  to 
show  wliat  remarkable  powers  some  tendrils  possess. 
The  species,  taken  together,  afford  connecting  links 


Fig.  5. 

Bignonia. 

Unnamed  species  from  Kew. 

between  twiners,  leaf-climbers,  tendril-bearers,  and  root- 
climbers. 

Bignonia  (an  unnamed  species  from  Kew,  closely 
allied  to  B.  unguis,  but  with  smaller  and  rather  broader 
leaves). — A  young  shoot  from  a  cut-down  plant  made 
three  revolutions  against  the  sun,  at  an  average  rate  of 
2  hrs.  6m.  The  stem  is  thin  and  flexible ;  it  twined 
round  a  slender  vertical  stick,  ascending  from  left  to 
right,  as  perfectly  and  as  regularly  as  any  true  twining- 
plant.  When  thus  ascending,  it  makes  no  use  of  its 
tendrils   or   petioles ;    but  when   it  twined  round   a 


Chap.  III.  BIGNONIACE.E.  87 

rather  thick  stick,  and  its  petioles  were  brought  into 
contact  with  it,  these  curved  round  the  stick,  showing 
that  they  have  some  degree  of  irritability.  The 
petioles  also  exhibit  a  slight  degree  of  spontaneous 
movement ;  for  in  one  case  they  certainly  described 
minute,  irregular,  vertical  ellipses.  The  tendrils  ap- 
parently curve  themselves  spontaneously  to  the  same 
side  with  the  petioles  ;  but  from  various  causes,  it  was 
difficult  to  observe  the  movement  of  either  the  tendrils 
or  petioles,  in  this  and  the  two  following  species. 
The  tendrils  are  so  closely  similar  in  all  respects  to 
those  of  B.  unguis,  that  one  description  will  suffice. 

Bignonia  unguis. — The  young  shoots  revolve,  but 
less  regularly  and  less  quickly  than  those  of  the' last 
species.  The  stem  twines  imperfectly  round  a  vertical 
stick,  sometimes  reversing  its  direction,  in  the  same 
manner  as  described  in  so  many  leaf-climbers ;  and 
this  plant  though  possessing  tendrils,  climbs  to  a 
certain  extent  like  a  leaf-climber.  Each  leaf  consists 
of  a  petiole  bearing  a  pair  of  leaflets,  and  terminates 
in  a  tendril,  which  is  formed  by  the  modification  of 
three  leaflets,  and  closely  resembles  that  above  figured 
(fig.  6).  But  it  is  a  little  larger,  and  in  a  young  plant 
was  about  half  an  inch  in  length.  It  is  curiously  like 
the  leg  and  foot  of  a  small  bird,  with  the  hind  toe  cut 
off.  The  straight  leg  or  tarsus  is  longer  than  the  three 
toes,  which  are  of  equal  length,  and  diverging,  lie  in 
the  same  plane.  The  toes  terminate  in  sharp,  hard 
claws,  much  curved  downwards,  like  those  on  a  bird's 
foot.     The  petiole  of  the  leaf  is  sensitive  to  contact ; 


88  TENDRIL-BEARERS.  Chap.  III. 

even  a  small  loop  of  thread  suspended  for  two  days 
caused  it  to  bend  upwards ;  but  the  sub-petioles  of 
the  two  lateral  leaflets  are  not  sensitive.  The  whole 
tendril,  namely,  the  tarsus  and  the  three  toes, 
are  likewise  sensitive  to  contact,  especially  on  their 
under  surfaces.  When  a  shoot  grows  in  the  midst  of 
thin  branches,  the  tendrils  are  soon  brought  by  the 
revolving  movement  of  the  internodes  into  contact 
with  them ;  and  then  one  toe  of  the  tendril  or  more, 
commonly  all  three,  bend,  and  after  several  hours  seize 
fast  hold  of  the  twigs,  like  a  bird  when  perched.  If 
the  tarsus  of  the  tendril  comes  into  contact  with  a 
twig,  it  goes  on  slowly  bending,  until  the  whole  foot 
is  carried  quite  round,  and  the  toes  pass  on  each  side 
of  the  tarsus  and  seize  it.  In  like  manner,  if  the  petiole 
comes  into  contact  with  a  twig,  it  bends  round,  carry- 
ing the  tendril,  which  then  seizes  its  own  petiole  or 
that  of  the  oj^posite  leaf.  The  petioles  move  spon- 
taneously, and  thus,  when  a  shoot  attempts  to  twine 
round  an  upright  stick,  those  on  both  sides  after  a  time 
come  into  contact  with  it,  and  are  excited  to  bend.' 
Ultimately  the  two  petioles  clasp  the  stick  in  oj^posite 
directions,  and  the  foot-like  tendrils,  seizing  on  each 
other  or  on  their  own  petioles,  fasten  the  stem  to  the 
support  with  surprising  security.  The  tendrils  are 
thus  brought  into  action,  if  the  &tem  twines  round  a 
thin  vertical  stick ;  and  in  this  respect  the  present 
species  differs  from  the  last.  Both  species  use  their 
tendrils  in  the  same  manner  when  passing  through  a 
thicket.    This  plant  is  one  of  the  most  efficient  climbers 


Chap.  III.  BIGNONIACE^.  89 

which  I  have  observed ;  and  it  probably  could  ascend 
a  polished  stem  incessantly  tossed  by  heavy  storms. 
To  show  how  important  vigorous  health  is  for  the 
action  of  all  the  parts,  I  may  mention  that  when  I 
first  examined  a  plant  which  was  growing  moderately 
well,  though  not  vigorously,  I  concluded  that  the 
tendrils  acted  only  like  the.  hooks  on  a  bramble,  and 
that  it  was  the  most  feeble  and  inefficient  of  all 
climbers  ! 

Bignonia  Tweedi/ana. — This  species  is  closely  allied 
to  the  last,  and  behaves  in  the  same  manner;  but 
perhaps  twines  rather  better  round  a  vertical  stick. 
On  the  same  plant,  one  branch  twined  in  one  direction 
and  another  in  an  opposite  direction.  The  internodes 
in  one  case  made  two  circles,  each  in  2  hrs.  33  m.  I 
was  enabled  to  observe  the  spontaneous  movements  of 
the  petioles  better  in  this  than  in  the  two  preceding 
species :  one  petiole  described  three  small  vertical 
ellipses  in  the  course  of  11  hrs.,  whilst  another 
moved  in  an  irregular  spire.  Some  little  time  after 
a  stem  has  twined  round  an  upright  stick,  and  is 
securely  fastened  to  it  by  the  clasping  petioles  and 
tendrils,  it  emits  aerial  roots  from  the  bases  of  its 
leaves ;  and  these  roots  curve  partly  round  and  adhere 
to  the  stick.  This  species  of  Bignonia,  therefore,  com- 
bines four  different  methods  of  climbing  generally 
characteristic  of  distinct  plants,  namely,  twining,  leaf- 
climbing,  tendril-climbing,  and  root-climbing. 

In  the  three  foregoing  species,  when  the  foot-like 
tendril  has   caught   an   object,  it  continues  to   grow 


90  ■  TENDKIL-BEAEEES.  Chap.  III. 

and  thicken,  and  ultimately  becomes  wonderfully 
strong,  in  the  same  manner  as  the  petioles  of  leaf- 
climbers.  If  the  tendril  catches  nothing,  it  first 
slowly  bends  downwards,  and  then  its  power  of  clasping 
is  lost.  Very  soon  afterwards  it  disarticulates  itself 
from  the  petiole,  and  drops  off  like  a  leaf  in  autumn. 
I  have  seen  this  process  of  disarticulation  in  no  other 
tendrils,  for  these,  when  they  fail  to  catch  an  object, 
merely  wither  away. 

Bignonia  venusta. — The  tendrils  diflfer  considerably 
from  those  of  the  previous  species.  The  lower  part, 
or  tarsus,  is  four  times  as  long  as  the  three  toes  ;  these 
are  of  equal  length  and  diverge  equally,  but  do  not 
lie  in  the  same  plane ;  their  tips  are  bluntly  hooked, 
and  the  whole  tendril  makes  an  excellent  grapnel.  The 
tarsus  is  sensitive  on  all  sides  ;  but  the  three  toes  are 
sensitive  only  on  their  outer  surfaces.  The  sensitive- 
ness is  not  much  developed  ;  for  a  slight  rubbing  with 
a  twig  did  not  cause  the  tarsus  or  the  toes  to  become 
curved  until  an  hour  had  elapsed,  and  then  only 
in  a  slight  degree.  Subsequently  they  straightened 
themselves.  Both  the  tarsus  and  toes  can  seize  well 
hold  of  sticks.  If  the  stem  is  secured,  the  tendrils  are 
seen  spontaneously  to  sweep  large  ellipses ;  the  two 
opposite  tendrils  moving  independently  of  one  another. 
I  have  no  doubt,  from  the  analogy  of  the  two  following 
allied  species,  that  the  petioles  also  move  spontaneously ; 
but  they  are  not  irritable  like  those  of  B.  unguis  and 
B.  Tiveedyana.  The  young  internodes  sweep  large 
circles,   one   being   completed   in  2  hrs.  15   m.,   and 


Chap.  III.  BIGNONIACE^.  91 

a  second  in  2  lirs.  oo  m.  By  these  combined  move- 
ments of  the  internodcs,  petioles,  and  j^rapnel-like 
tendrils,  the  latter  are  soon  brought>  into  contact  with 
surrounding  objects.  When  a  shoot  stands  near  an 
upright  stick,  it  twines  regularly  and  spirally  round 
it.  As  it  ascends,  it  seizes  the  stick  with  one  of  its 
tendrils,  and,  if  the  stick  be  thin,  the  right-  and  left- 
hand  tendrils  are  alternately  used.  This  alternation 
follows  from  the  stem  necessarily  taking  one  twist 
round  its  own  axis  for  each  completed  circle. 

The  tendrils  contract  spirally  a  short  time  after 
catching  any  object;  those  which  catch  nothing  merely 
bend  slowly  downwards.  But  the  whole  subject  of 
the  spiral  contraction  of  tendrils  will  be  discussed 
after  all  the  tendril-bearing  species  have  been  de- 
scribed. 

Bignonia  littoralis. — The  young  intemodes  revolve 
in  large  ellipses.  An  internode  bearing  immature 
tendrils  made  two  revolutions,  each  in  3  hrs.  50  m. ; 
but  when  grown  older  with  the  tendrils  mature,  it 
made  two  ellipses,  each  at  the  rate  of  2  hrs.  44  m. 
This  species,  unlike  the  preceding,  is  incapable  of 
twining  round  a  stick  :  this  does  not  appear  to  be 
due  to  any  want  of  flexibility  in  the  intemodes  or 
to  the  action  of  the  tendrils,  and  certainly  not  to 
any  want  of  the  revolving  power ;  nor  can  I  account 
for  the  fact.  Nevertheless  the  plant  readily  ascends 
a  thin  upright  stick  by  seizing  a  point  above  with  its 
two  opposite  tendrils,  which  then  contract  spirally.  If 
the  tendrils  seize  nothing,  they  do  not  become  spiral. 


92  TENDRTL-BEARERS.  Chap.  III. 

The  species  last  described,  ascended  a  vertical  stick 
by  twining  spirally  and  by  seizing  it  alternately  with 
its  opposite  tendrils,  like  a  sailor  pulling  himself  up 
a  rope,  hand  over  hand  ;  the  present  species  pulls  itself 
up,  like  a  sailor  seizing  with  both  hands  together  a 
roj)e  above  his  head. 

The  tendrils  are  similar  in  structure  to  those  of  the 
last  species.  They  continue  growing  for  some  time, 
even  after  they  have  clasped  an  object.  When  fully 
grown,  though  borne  by  a  young  plant,  they  are  9  inches 
in  length.  The  three  divergent  toes  are  shorter  re- 
latively to  the  tarsus  than  in  the  former  species ;  they 
are  blunt  at  their  tijis  and  but  slightly  hooked ;  they 
are  not  quite  equal  in  length,  the  middle  one  being 
rather  longer  than  the  others.  Their  outer  surfaces 
are  highly  sensitive ;  for  when  lightly  rubbed  with 
a  twig,  they  became  perceptibly  curved  in  4  m.  and 
greatly  curved  in  7  m.  In  7  hrs.  they  became  straight 
again  and  were  ready  to  re-act.  The  tarsus,  for  the 
space  of  one  inch  close  to  the  toes,  is  sensitive,  but 
in  a  rather  less  degree  than  the  toes ;  for  the  latter, 
after  a  slight  rubbing,  became  curved  in  about  half  the 
time.  Even  the  middle  part  of  the  tarsus  is  sensitive 
to  prolonged  contact,  as  soon  as  the  tendril  has  arrived 
at  maturity.  After  it  has  grown  old,  the  sensitiveness 
is  confined  to  the  toes,  and  these  are  only  able  to  curl 
very  slowly  round  a  stick.  A  tendril  is  perfectly  ready 
to  act,  as  soon  as  the  three  toes  have  diverged,  and 
at  this  period  their  outer  surfaces  first  become  irritable. 
The  irritability  spreads  but  little  from  one  part  when 


Chap.  III.  BIGNONIACE^.  93 

excited  to  another :  tlius,  when  a  stick  was  caught  by 
the  part  immediately  beneath  the  three  toes,  these 
seklom  cksped  it,  but  remained  sticking  straight  out. 

The  tendrils  revolve  spontaneously.  The  movement 
begins  before  the  tendril  is  converted  into  a  three- 
pronged  grapnel  by  the  divergence  of  the  toes,  and 
before  any  part  has  become  sensitive ;  so  that  the 
revolving  movement  is  useless  at  this  early  period. 
The  movement  is,  also,  now  slow,  two  ellipses  being 
completed  conjointly  in  24  hrs.  18  m.  A  mature  ten- 
dril made  an  ellipse  in  6  hrs. ;  so  that  it  moved  much 
more  slowly  than  the  internodes.  The  ellipses  which 
were  swept,  both  in  a  vertical  and  horizontal  plane, 
were  of  large  size.  The  petioles  are  not  in  the  least 
sensitive,  but  revolve  like  the  tendrils.  We  thus  see 
that  the  young  internodes,  the  petioles,  and  the  ten- 
drils all  continue  revolving  together,  but  at  different 
rates.  The  movements  of  the  tendrils  which  rise 
opposite  one  another  are  quite  independent.  Hence, 
when  the  whole  shoot  is  allowed  freely  to  revolve, 
nothing  can  be  more  intricate  than  the  course  followed 
by  the  extremity  of  each  tendril.  A  wide  space  is 
thus  irregularly  searched  for  some  object  to  be 
grasped. 

One  other  curious  point  remains  to  be  mentioned. 
In  the  course  of  a  few  days  after  the  toes  have  closely 
clasped  a  stick,  their  blunt  extremities  become  de- 
veloped, though  not  invariably,  into  irregular  disc- 
like balls  which  have  the  power  of  adhering  firmly  to 
the   wood.     As  similiar   cellular   outgrowths  will   be 


94  TENDKIL-BEAREES.  Cuap.  III. 

fully  described  under  B.  cajoreolata,  I  will  here  say 
nothing  more  about  them. 

Bignonia  sequinodialis,  var.  Cliaiiiberlmjiiii. — The 
internodes,  the  elongated  non-sensitive  petioles,  and 
the  tendrils  all  revolve.  The  stem  does  not  twine, 
but  ascends  a  vertical  stick  in  the  same  manner  as 
the  last  species.  The  tendrils  also  resemble  those  of 
the  last  species,  but  are  shorter;  the  three  toes  are 
more  unequal  in  length,  the  two  outer  ones  being 
about  one-third  shorter  and  rather  thinner  than  the 
middle  toe ;  but  they  vary  in  this  respect.  They 
terminate  in  small  hard  points ;  and  what  is  important, 
cellular  adhesive  discs  are  not  developed.  The  re- 
duced size  of  two  of  the  toes  as  well  as  their  lessened 
sensitiveness,  seem  to  indicate  a  tendency  to  abortion  ; 
and  on  one  of  my  plants  the  first-formed  tendrils  were 
sometimes  simple,  that  is,  were  not  divided  into  three 
toes.  We  are  thus  naturally  led  to  the  three  following 
species  with  undivided  tendrils  : — 

Bignonia  speciosa. — The  young  shoots  revolve  irregu- 
larly, making  narrow  ellipses,  spires  or  circles,  at  rates 
varying  from  3  hrs.  30  m.  to  4  hrs.  40  m. ;  but  they 
show  no  tendency  to  twine.  Whilst  the  plant  is 
young  and  does  not  require  a  support,  tendrils  are 
not  developed.  Those  borne  by  a  moderately  young 
plant  were  five  inches  in  length.  They  revolve  spon- 
taneously, as  do  the  short  and  non-sensitive  petioles. 
When  rubbed,  they  slowly  bend  to  the  rubbed  side 
and  subsequently  straighten  themselves  ;  but  they  are 
not  highly  sensitive.     There  is  something  strange  in 


Chap.  III.  BIGN0NIACEJ3.  95 

their  behaviour :  I  repeatedly  placed  close  to  them, 
thick  and  thin,  rough  and  smooth  sticks  and  posts,  as 
well  as  string  suspended  vertically,  but  none  of  these 
objects  were  well  seized.  After  clasping  an  upright 
stick,  they  repeatedly  loosed  it  again,  and  often  would 
not  seize  it  at  all,  or  their  extremities  did  not  coil 
closely  round.  I  have  observed  hundreds  of  tendrils 
belonging  to  various  Cucurbitaceous,  Passifloraceous, 
and  Leguminous  plants,  and  never  saw  one  behave  in 
this  manner.  When,  however,  my  plant  had  grown 
to  a  height  of  eight  or  nine  feet,  the  tendrils  acted 
much  better.  They  now  seized  a  thin,  upright  stick 
horizontally,  that  is,  at  a  point  on  their  own  level,  and 
not  some  way  up  the  stick  as  in  the  case  of  all  the 
previous  species.  Nevertheless,  the  non-twining  stem 
was  enabled  by  this  means  to  ascend  the  stick. 

The  extremity  of  the  tendril  is  almost  straight  and 
sharp.  The  whole  terminal  portion  exhibits  a  singular 
habit,  which  in  an  animal  would  be  called  an  instinct ; 
for  it  continually  searches  for  any  little  crevice  or  hole 
into  which  to  insert  itself.  I  had  two  young  plants ; 
and,  after  having  observed  this  habit,  I  placed  near 
them  posts,  which  had  been  bored  by  beetles,  or  had 
become  fissured  by  drying.  The  tendrils,  by  their 
own  movement  and  by  that  of  the  internodes,  slowly 
travelled  over  the  surface  of  the  wood,  and  when  the 
apex  came  to  a  hole  or  fissure  it  inserted  itself;  in 
order  to  effect  this  the  extremity  for  a  length  of  half 
or  quarter  of  an  inch,  wotild  often  bend  itself  at  right 
angles  to  the  basal  part.     I  have  watched  this  process 


96  TENDEIL-BEARERS.  Chap.  III. 

between  twenty  and  thirty  times.  The  same  tendril 
would  frequently  withdraw  from  one  hole  and  insert 
its  point  into  a  second  hole.  I  have  also  seen  a 
tendril  keep  its  point,  in  one  case  for  20  hrs.  and  in 
another  for  36  hrs.,  in  a  minute  hole,  and  then  with- 
draw it.  Whilst  the  point  is  thus  temporarily  inserted, 
the  opposite  tendril  goes  on  revolving. 

The  whole  length  of  a  tendril  often  fits  itself  closely 
to  any  surface  of  wood  with  which  it  has  come  into 
contact ;  and  I  have  observed  one  bent  at  right  angles, 
from  having  entered  a  wide  and  deep  fissure,  with  its 
apex  abruptly  re-bent  and  inserted  into  a  minute 
lateral  hole.  After  a  tendril  has  clasi^ed  a  stick,  it 
contracts  s^sirally ;  if  it  remains  unattached  it  hangs 
straight  downwards.  If  it  has  merely  adapted  itself  to 
the  inequalities  of  a  thick  post,  though  it  has  clasped 
nothing,  or  if  it  has  inserted  its  apex  into  some  little 
fissure,  this  stimulus  suffices  to  induce  spiral  contrac- 
tion ;  but  the  contraction  always  draws  the  tendril 
away  from  the  post.  So  that  in  every  case  these 
movements,  which  seem  so  nicely  adapted  for  some 
purpose,  were  useless.  On  one  occasion,  however, 
the  tip  became  permanently  jammed  into  a  narrow 
fissure.  I  fvilly  expected,  from  the  analogy  of  B. 
capreolata  and  B.  littordlis,  that  the  tips  would  have 
been  developed  into  adhesive  discs;  but  I  could 
never  detect  even  a  trace  of  this  process.  There 
is  therefore  at  present  something  unintelligible  about 
the  habits  of  this  plant. 

Bignonia  pida. — This  species  closely  resembles  the 


Chap.  IIL  BIGNONIACE^.  97 

last  in  the  structure  and  movements  of  its  tendrils.  I 
also  casually  examined  a  fine  growing  plant  of  the 
allied  B.  Lindleyi,  and  this  apparently  behaved  in  all 
respects  in  the  same  manner. 

Bignonia  capreolata. — We  now  come  to  a  species 
having  tendrils  of  a  different  type ;  but  first  for  the 
internodes.  A  young  shoot  made  three  large  revolu- 
tions, following  the  sun,  at  an  average  rate  of  2  hrs.  23  m. 
The  stem  is  thin  and  flexible,  and  I  have  seen  one 
make  four  regular  spiral  turns  round  a  thin  upright 
stick,  ascending  of  course  from  right  to  left,  and 
therefore  in  a  reversed  direction  compared  with  the 
before  described  species.  Afterwards,  from  the  inter- 
ference of  the  tendrils,  it  ascended  either  straight  up 
the  stick  or  in  an  irregular  spire.  The  tendrils  are 
in  some  respects  highly  remarkable.  In  a  young 
plant  they  were  about  2^  inches  in  length  and  much 
branched,  the  five  chief  branches  apparently  repre- 
senting two  pairs  of  leaflets  and  a  terminal  one.  Each 
branch  is,  however,  bifid  or  more  commonly  trifid  towards 
the  extremity,  with  the  points  blunt  yet  distinctly 
hooked.  A  tendril  bends  to  any  side  which  is  lightly 
rubbed,  and  subsequently  becomes  straight  again ; 
but  a  loop  of  thread  weighing  |th  of  a  grain  produced 
no  effect.  On  two  occasions  the  terminal  branches 
became  slightly  curved  in  10  m.  after  they  had  touched 
a  stick  ;  and  in  30  m.  the  tips  were  curled  quite  round 
it.  The  basal  part  is  less  sensitive.  The  tendrils  re- 
volved in  an  apparently  capricious  manner,  sometimes 
very   slightly   or  not   at  all;    at    other    times    they 


98  TENDEIL-BEAEERS.  Chap.  III. 

described  large  regular  ellijpses.      I  could  detect  no 
spontaneous  movement  in  tlie  petioles  of  the  leaves. 

Whilst  the  tendrils  are  revolving  more  or  less 
regularly,  another  remarkable  movement  takes  place, 
namely,  a  slow  inclination  from  the  light  towards 
the  darkest  side  of  the  house.  I  repeatedly  changed 
die  position  of  my  plants,  and  some  little  time  after 
the  revolving  movement  had  ceased,  the  successively 
formed  tendrils  always  ended  by  pointing  to  the 
darkest  side.  When  I  placed  a  thick  post  near  a 
tendril,  between  it  and  the  light,  the  tendril  pointed 
in  that  direction.  In  two  instances  a  pair  of  leaves 
stood  so  that  one  of  the  two  tendrils  was  directed 
towards  the  light  and  the  other  to  the  darkest  side  of 
the  house ;  the  latter  did  not  move,  but  the  opposite 
one  bent  itself  first  upwards  and  then  right  over  its 
fellow,  so  that  the  two  became  parallel,  one  above  the 
other,  both  pointing  to  the  dark :  I  then  turned  the 
plant  half  round ;  and  the  tendril  which  had  turned 
over  recovered  its  original  position,  and  the  opposite 
one  which  had  not  before  moved,  now  turned  over  to 
the  dark  side.  Lastly,  on  another  plant,  three  pairs 
of  tendrils  were  produced  at  the  same  time  by  three 
shoots,  and  all  happened  to  be  differently  directed :  I 
placed  the  pot  in  a  box  open  only  on  one  side,  and 
obliquely  facing  the  light ;  in  two  days  all  six  ten- 
drils pointed  with  unerring  truth  to  the  darkest  corner 
of  the  box,  though  to  do  this  each  had  to  bend  in  a 
different  manner.  Six  wind-vanes  could  not  have 
more  truly  shown  the  direction  of  the  wind,  than  did 


Cit AT.  III.  BIGNONIACE^.  99 

these  branched  tendrils  the  course  of  the  stream  of 
light  which  entered  the  box.  I  left  these  tendrils 
undisturbed  for  above  24  hrs.,  and  then  turned  the 
pot  half  round ;  but  they  had  now  lost  their  power  of 
movement,  and  could  not  any  longer  avoid  the  light. 

When  a  tendril  has  not  succeeded  in  clasping  a 
support,  either  through  its  own  revolving  movement  or 
that  of  the  shoot,  or  by  turning  towards  any  object 
which  intercepts  the  light,  it  bends  vertically  down- 
wards and  then  towards  its  own  stem,  which  it  seizes 
together  with  the  supporting  stick,  if  there  be  one. 
A  little  aid  is  thus  given  in  keeping  the  stem  secure. 
If  the  tendril  seizes  nothing,  it  does  not  contract 
spirally,  but  soon  withers  away  and  drops  off.  If  it 
seizes  an  object,  all  the  branches  contract  spirally. 

I  have  stated  that  after  a  tendril  has  come  into 
contact  with  a  stick,  it  bends  round  it  in  about  half 
an  hour ;  but  I  repeatedly  observed,  as  in  the  case 
of  B.  speciosa  and  its  allies,  that  it  often  again  loosed 
the  stick  ;  sometimes  seizing  and  loosing  the  same  stick 
three  or  four  times.  Knowing  that  the  tendrils  avoided 
the  light,  I  gave  them  a  glass  tube  blackened  within, 
and  a  well-blackened  zinc  plate :  the  branches  curled 
round  the  tube  and  abruptly  bent  themselves  round 
the  edges  of  the  zinc  plate ;  but  they  soon  recoiled 
from  these  objects  with  what  I  can  only  call  disgust, 
and  straightened  themselves.  I  then  placed  a  post 
with  extremely  rugged  bark  close  to  a  pair  of  tendrils ; 
twice  they  touched  it  for  an  hour  or  two,  and  twice 
they  withdrew ;  at  last  one  of  the  hooked  extremities 


100  TENDRIL-BEAEERS.  Chap.  m. 

curled  round  and  firmly  seized  an  excessively  minute 
projecting  point  of  bark,  and  then  the  other  branches 
spread  themselves  out,  following  with  accuracy  every 
inequality  of  the  surface.  I  afterwards  placed  near 
the  plant  a  post  without  bark  but  much  fissured,  and 
the  points  of  .the  tendrils  crawled  into  all  the  crevices 
in  a  beautiful  manner.  To  my  surprise,  I  observed 
that  the  tips  of  the  immature  tendrils,  with  the 
branches  not  yet  fully  separated,  likewise  crawled 
just  like  roots  into  the  minutest  crevices.  In  two 
or  three  days  after  the  tips  had  thus  crawled  into 
the  crevices,  or  after  their  hooked  ends  had  seized 
minute  points,  the  final  process,  now  to  be  described, 
commenced. 

This  process  I  discovered  by  having  accidentally 
left  a  piece  of  wool  near  a  tendril ;  and  this  led  me  to 
bind  a  Quantity  of  flax,  moss,  and  wool  loosely  round 
sticks,  and  to  place  them  near  tendrils.  The  wool  must 
not  be  dyed,  for  these  tendrils  are  excessively  sensitive 
to  some  poisons.  The  hooked  points  soon  caught  hold 
of  the  fibres,  even  loosely  floating  fibres,  and  now  there 
was  no  recoiling ;  on  the  contrary,  the  excitement 
caused  the  hooks  to  penetrate  the  fibrous  mass  and 
to  curl  inwards,  so  that  each  hook  caught  firmly  one 
or  two  fibres,  or  a  small  bundle  of  them.  The  tips 
and  the  inner  surfaces  of  the  hooks  now  began  to  swell, 
and  in  two  or  three  days  were  visibly  enlarged.  After 
a  few  more  days  the  hooks  were  converted  into  whitish, 
irregular  balls,  rather  above  the  g'otli  of  an  inch  (1-27 
mm.)  in  diameter,  formed  of  coarse   cellulnr  tissue, 


Chap.  III.  BIGNONIACE^.  101 

which  sometimes  wholly  enveloped  and  concealed  the 
hooks  themselves.  The  surfaces  of  these  balls  secrete 
some  viscid  resinous  matter,  to  which  the  fibres  of  the 
flax,  &c.,  adhere.  When  a  fibre  has  become  fastened 
to  the  surface,  the  cellular  tissue  does  not  grow 
directly  beneath  it,  but  continues  to  grow  closely  on 
each  side ;  so  that  when  several  adjoining  fibres, 
though  excessively  thin,  were  caught,  so  many  crests 
of  cellular  matter,  each  not  as  thick  as  a  human  hair, 
grew  up  between  them,  and  these,  arching  over  on 
both  sides,  adhered  firmly  together.  As  the  whole 
surface  of  the  ball  continues  to  grow,  fresh  fibres 
adhere  and  are  afterwards  enveloped ;  so  that  I  have 
seen  a  little  ball  with  between  fifty  and  sixty  fibres 
of  flax  crossing  it  at  various  angles  and  all  embedded 
more  or  less  deeply.  Every  gradation  in  the  process 
could  be  followed — some  fibres  merely  sticking  to 
the  surface,  others  lying  in  more  or  less  deep  furrows, 
or  deeply  embedded,  or  passing  through  the  very 
centre  of  the  cellular  ball.  The  embedded  fibres  are 
so  closely  clasped  that  they  cannot  be  withdrawn. 
The  outgrowing  tissue  has  so  strong  a  tendency  to 
unite,  that  two  balls  produced  by  distinct  tendrils 
sometimes  unite  and  grow  into  a  single  one. 

On  one  occasion,  when  a  tendril  had  curled  round 
a  stick,  half  an  inch  in  diameter,  an  adhesive  disc 
Avas  formed ;  but  this  does  not  generally  occur  in  the 
case  of  smooth  sticks  or  posts.  If,  however,  the  tip 
catches  a  minute  projecting  point,  the  other  branches 
form   discs,  especially  if  they  find  crevices  to  crawl 


102  TENDRIL-BEAKEES.  CllAP.  lU. 

into.  The  tendrils  failed  to  attach  themselves  to  a 
brick  wall. 

I  infer  from  the  adherence  of  the  fibres  to  the  discs 
or  balls,  that  these  secrete  some  resinous  adhesive 
matter;  and  more  especially  from  such  fibres  becoming 
loose  if  immersed  in  sulphuric  ether.  This  fluid  like- 
wise removes^  small,  brown,  glistening  points  which  can 
generally  be  seen  on  the  surfaces  of  the  older  discs. 
If  the  hooked  extremities  of  the  tendrils  do  not  touch 
anything,  discs,  as  far  as  I  have  seen,  are  never 
formed;*  but  temporary  contact  during  a  moderate 
time  suffices  to  cause  their  development.  I  have  seen 
eight  discs  formed  on  the  same  tendril.  After  their 
develo23ment  the  tendrils  contract  spirally,  and  become 
woody  and  very  strong.  A  tendril  in  this  state  sup- 
ported nearly  seven  ounces,  and  would  apparently  have 
supported  a  considerably  greater  weight,  had  not  the 
fibres  of  flax  to  which  the  discs  were  attached  yielded. 

From  the  facts  now  given,  we  may  infer  that  though 
the  tendrils  of  this  Bignonia  can  occasionally  adhere 
to  smooth  cylindrical  sticks  and  often  to  rugged  bark, 
yet  that  they  are  specially  adapted  to  climb  trees 
clothed  with  lichens,  mosses,  or  other  such  productions ; 
and  I  hear  from  Professor  Asa  Gray  that  the  Polypodium 
incanum  abounds  on  the  forest-trees  in  the  districts  of 


*  Fritz  Miiller  states  (ibid.  p.  object,  terminate  in  smooth  shining 

348)  that    in  South    Brazil   the  discs.    These,   however,  after  ad- 

trifid    tendrils   of  Haplolophium,  hering  to  any'  object,  sometimes 

(one  of  the  Bignoniacese)  without  become  considerably  enlaiged. 
liaving  come  into  contact  with  any 


Chap.  III.  BIGNONIACEiE.  103 

North  America  where  this  species  of  Bignonia  grows. 
Finally,  I  may  remark  how  singular  a  fact  it  is  that 
a  leaf  should  be  metamorphosed  into  a  branched 
organ  which  turns  from  the  light,  and  which  can 
by  its  extremities  either  crawl  like  roots  into  crevices, 
or  seize  hold  of  minute  projecting  points,  these  ex- 
tremities afterwards  forming  cellular  outgrowths  which 
secrete  an  adhesive  cement,  and  then  envelop  by  their 
continued  growth  the  finest  fibres. 

Eccremocaryus  scaber  {Bignoniacese). — Plants,  though 
growing  pretty  well  in  my  green-house,  showed  no 
spontaneous  movements  in  their  shoots  or  tendrils ; 
but  when  removed  to  the  hot-house,  the  young  inter- 
nodes  revolved  at  rates  varying  from  3  hrs.  15  m.  to 
1  hr.  13  m.  One  large  circle  was  swept  at  this  latter 
unusually  quick  rate ;  but  generally  the  circles  or 
ellipses  were  small,  and  sometimes  the  course  pursued 
was  quite  irregular.  An  internode,  after  making  several 
revolutions,  sometimes  stood  still  for  12  hrs.  or  18  hrs., 
and  then  recommenced  revolving.  Such  strongly  marked 
interruptions  in  the  movements  of  the  internodes  I 
have  observed'  in  hardly  any  other  plant. 

The  leaves  bear  four  leaflets,  themselves  subdivided, 
and  terminate  in  much-branched  tendrils.  The 
main  petiole  of  the  leaf,  whilst  young,  moves  sponta- 
neously, and  follows  nearly  the  same  irregular  course 
and  at  about  the  same  rate  as  the  internodes.  The 
movement  to  and  from  the  stem  is  the  most  con- 
spicuous, and  I  have  seen  the  chord  of  a  curved  petiole 
which  formed  an  ang-le  of  59°  with  the  stem,  in  an 


104  TENDRIL-BEAREES.  Coap.  Ill 

hour  afterwards  making  an  angle  of  106°.  The  two 
opposite  petioles  do  not  move  together,  and  one  is 
sometimes  so  much  raised  as  to  stand  close  to  the  stem, 
whilst  the  other  is  not  far  from  horizontal.  The  basal 
part  of  the  petiole  moves  less  than  the  distal  part.  The 
tendrils,  besides  being  carried  by  the  moving  petioles 
and  internodes,  themselves  move  spontaneously ;  and 
the  opposite  tendrils  occasionally  move  in  opposite 
directions.  By  these  combined  movements  of  the 
young  internodes,  petioles,  and  tendrils,  a  considerable 
space  is  swept  in  search  of  a  support. 

In  young  plants  the  tendrils  are  about  three  inches 
in  length :  they  bear  two  lateral  and  two  terminal 
branches ;  and  each  branch  bifurcates  twice,  with  the 
tips  terminating  in  blunt  double  hooks,  having  both 
points  directed  to  the  same  side.  All  the  branches  are 
sensitive  on  all  sides ;  and  after  being  lightly  rubbed, 
or  after  coming  into  contact  with  a  stick,  bend  in 
about  10  m.  One  which  had  become  curved  in  10  m. 
after  a  light  rub,  continued  bending  for  between  3  hrs. 
and  4  hrs.,  and  became  straight  again  in  8  hrs.  or 
9  hrs.  Tendrils,  which  have  caught  nothing,  ultimately 
contract  into  an  irregular  spire,  as  they  likewise  do, 
only  much  more  quickly,  after  clasping  a  support.  In 
both  cases  the  main  petiole  bearing  the  leaflets,  which 
is  at  first  straight  and  inclined  a  little  upwards, 
rtioves  downwards,  with  the  middle  part  bent  abruptly 
into  a  right  angle ;  but  this  is  seen  in  E.  miniatus 
more  plainly  than  in  E.  scdher.  The  tendrils  in  this 
genus  act   in  some   respects   like   those   of  Bignonia 


CuAP.  III.  BIGNONIACE^.  105 

capreolata;  but  the  whole  does  not  move  from  the 
light,  nor  do  the  hooked  tips  become  enlarged  into  cel- 
lular discs.  After  the  tendrils  have  come  into  contact 
with  a  moderately  thick  cylindrical  stick  or  Avith 
rugged  bark,  the  several  branches  may  be  seen  slowly 
to  lift  themselves  up,  change  their  positions,  and 
again  come  into  contact  with  the  supporting  surface. 
The  object  of  these  movements  is  to  bring  the  double 
hooks  at  the  extremities  of  the  branches,  which  natu- 
rally face  in  all  directions,  into  contact  with  the  wood. 
I  have  watched  a  tendril,  half  of  which  had  bent  itself 
at  right  angles  round  the  sharp  corner  of  a  square  post, 
neatly  bring  every  single  hook  into  contact  with  both 
rectangular  surfaces.  The  appearance  suggested  the 
belief,  that  though  the  whole  tendril  is  not  sensitive  to 
light,  yet  that  the  tips  are  so,  and  that  they  turn 
and  twist  themselves  towards  any  dark  surface.  Ulti- 
mately the  branches  arrange  themselves  very  neatly 
to  all  the  irregularities  of  the 'most  rugged  bark,  so 
that  they  resemble  in  their  irregular  course  a  river 
with  its  branches,  as  engraved  on  a  map.  But  when 
a  tendril  has  wound  round  a  rather  thick  stick,  the 
subsequent  spiral  contraction  generally  draws  it  away 
and  spoils  the  neat  arrangement.  So  it  is,  but  not  in 
quite  so  marked  a  manner,  when  a  tendril  has  sj)read 
itself  over  a  large,  nearly  flat  surface  of  rugged  bark. 
We  may  therefore  conclude  that  these  tendrils  are  not 
perfectly  adapted  to  seize  moderately  thick  sticks  or 
rugged  bark.  If  a  thin  stick  or  twig  is  placed  near 
a  tendril,  the  terminal  branches  wind  quite  round  it, 


106  TENDEIL-BEAREES.  Chap.  III. 

and  then  seize  their  own  lower  branches  or  the  main 
stem.  The  stick  is  thus  firmly,  but  not  neatly, 
grasped.  What  the  tendrils  are  really  adapted  for, 
appears  to  be  such  objects  as  the  thin  culms  of  certain 
grasses,  or  the  long  flexible  bristles  of  a  brush,  or  thin 
rigid  leaves  such  as  those  of  the  Asparagus,  all  of 
which  they  seize  in  an  admirable  manner.  This  is 
due  to  the  extremities  of  the  branches  close  to  the 
little  hooks  being  extremely  sensitive  to  a  touch 
from  the  thinnest  object,  which  they  consequently 
curl  round  and  clasp.  When  a  small  brush,  for 
instance,  was  placed  near  a  tendril,  the  tips  of  each 
sub-branch  seized  one,  two,  or  three  of  the  bristles ; 
and  then  the  spiral  contraction  of  the  several  branches 
brought  all  these  little  parcels  close  together,  so  that 
thirty  or  forty  bristles  were  drawn  into  a  single  bundle, 
which  afforded  an  excellent  support. 

PoLEMONiACEiE.  —  Cohwa  scandens. —  This  is  an 
excellently  constructed  climber.  The  tendrils  on  a 
fine  plant  were  eleven  inches  long,  with  the  petiole 
bearing  two  pairs  of  leaflets,  only  two  and  a  half 
inches  in  length.  They  revolve  more  rapidly  and 
vigorously  than  those  of  any  other  tendril-bearer 
observed  by  me,  with  the  exception  of  one  kind  of 
Passijlora.  Three  large,  nearly  circular  sweeps,  di- 
rected against  the  sun  were  completed,  each  in  1  hr. 
15  m.;  and  two  other  circles  in  1  hr.  20  m.  and  1  hr. 
23  m.  Sometimes  a  tendril  travels  in  a  much  inclined 
position,  and  sometimes  nearly  upright.  The  lower  part 
moves  but  little  and  the  petiole  not  at  all;  nor  do 


Chap.  ]  II.  POLEMONIACE^.  107 

the  internodes  revolve ;  so  that  here  we  have  the  tendril 
alone  moving.  On  the  other  hand,  with  most  of  the 
species  of  Bignonia  and  the  Eccremocarpus,  the  inter- 
nodes, tendrils,  and  petioles  all  revolved.  The  long, 
straight,  tapering  main  stem  of  the  tendril  of  the  Cobiea 
bears  alternate  branches ;  and  each  branch  ia  several 
times  divided,  with  the  finer  branches  as  thin  as  very 
thin  bristles  and  extremely  flexible,  so  that  they  are 
blown  about  by  a  breath  of  air ;  yet  they  are  strong 
and  highly  elastic.  The  extremity  of  each  branch  is  a 
little  flattened,  and  terminates  in  a  minute  double 
(though  sometimes  single)  hook,  formed  of  a  hard,  trans- 
lucent, woody  substance,  and  ,  as  sharp  as  the  finest 
needle.  On  a  tendril  which  was  eleven  inches  Ions;  1 
counted  ninety-four  of  these  beautifully  constructed 
little  hooks.  They  readily  catch  soft  wood,  or  gloves, 
or  the  skin  of  the  naked  hand.  With  the  exception  of 
these  hardened  hooks,  and  of  the  basal  part  of  the  central 
stem,  every  part  of  every  branchlet  is  highly  sensitive 
on  all  sides  to  a  slight  touch,  and  bends  in  a  few 
minutes  towards  the  touched  side.  By  lightly  rub- 
bing several  sub-branches  on  opposite  sides,  the  whole 
tendril  rapidly  assumed  an  extraordinarily  crooked 
shape.  These  movements  from  contact  do  not  inter- 
fere with  the  ordinary  revolving  movement.  The 
branches,  after  becoming  greatly  curved  from  being- 
touched,  straighten  themselves  at  a  quicker  rate  than 
in  almost  any  other  tendril  seen  by  me,  namely,  in 
between  half  an  hour  and  an  hour.  After  the  tendril 
has   caught   any   object,    spiral    contraction   likewise 


108  TENDRIL-BEAREES.  Chap.  III. 

begins   after   an    unusually   short    interval    of    time, 
namely,  in  about  twelve  hours. 

Before  the  tendril  is  mature,  the  terminal  branchlets 
cohere,  and  the  hooks  are  curled  closely  inwards.  At 
this  period  no  part  is  sensitive  to  a  touch ;  but  as  soon 
as  the  branches  diverge  and  the  hooks  stand  out,  full 
sensitiveness  is  acquired.  It  is  a  singular  circumstance 
that  immature  tendrils  revolve  at  their  full  velocity 
before  they  become  sensitive,  but  in  a  useless  manner, 
as  in  this  state  they  can  catch  nothing.  This  want 
of  perfect  co-adaptation,  though  only  for  a  short  time, 
between  the  structure  and  the  functions  of  a  climbing- 
plant  is  a  rare  event.  A  tendril,  as  soon  as  it  is  ready 
to  act,  stands,  together  with  the  supporting  petiole, 
vertically  upwards.  The  leaflets  borne  by  the  petiole 
are  at  this  time  quite  small,  and  the  extremity  of  the 
growing  stem  is  bent  to  one  side  so  as  to  be  out 
of  the  way  of  the  revolving  tendril,  which  sweeps 
large  circles  directly  over  head.  The  tendrils  thus 
revolve  in  a  position  well  adapted  for  catching  objects 
standing  above ;  and  by  this  means  the  ascent  of  the 
plant  is  favoured.  If  no  object  is  caught,  the  leaf 
with  its  tendril  bends  downwards  and  ultimately 
assumes  a  horizontal  position.  An  open  space  is 
thus  left  for  the  next  succeeding  and  younger  tendril 
to  stand  vertically  upwards  and  to  revolve  freely. 
As  soon  as  an  old  tendril  bends  downwards,  it  loses 
all  power  of  movement,  and  contracts  spirally  into  an 
entangled  mass.  Although  the  tendrils  revolve  with 
unusual  rapidity,  the  movement  lasts  for  only  a  short 


Chap.  III.  POLEMONIACE^E.  109 

time.  In  a  plant  placed  in  the  hot-house  and  grow- 
in*^  vigorously,  a  tendril  revolved  for  not  longer  than 
36  hours,  counting  from  the  period  when  it  first  became 
sensitive ;  but  during  this  period  it  probably  made  at 
least  27  revolutions. 

When  a  revolving  tendril  strikes  against  a  stick, 
the  branches  quickly  bend  round  and  clasp  it.  The 
little  hooks  here  play  an  important  part,  as  they 
prevent  the  branches  from  being  dragged  away  by  the 
rapid  revolving  movement,  before  they  have  had  time 
to  clasp  the  stick  securely.  This  is  especially  the  case 
when  only  the  extremity  of  a  branch  has  caught 
hold  of  a  support.  As  soon  as  a  tendril  has  bent 
round  a  smooth  stick  or  a  thick  rugged  post,  or  has 
come  into  contact  with  planed  wood  (for  it  can  adhere 
temporarily  even  to  so  smooth  a  surface  as  this),  the 
same  peculiar  movements  may  be  observed  as  those 
described  under  Bignonia  capreolata  and  Eccremocar- 
2)us.  The  branches  repeatedly  lift  themselves  up  and 
down ;  those  which  have  their  hooks  already  directed 
downwards  remaining  in  this  position  and  securing 
the  tendril,  whilst  the  others  twist  about  until  they 
succeed  in  arranging  themselves  in  conformity  ^ith 
every  irregularity  of  the  surface,  and  in  bringing 
their  hooks  into  contact  with  the  wood.  The  use  of 
the  hooks  was  well  shown  by  giving  the  tendrils 
tubes  and  slips  of  glass  to  catch;  for  these,  though 
temporarily  seized,  were  invariably  lost,  either  during 
the  re-arrangement  of  the  branches  or  ultimately  when 
spiral  contraction  ensued. 


110  TENDRIL-BE AKEES.  Chap.  III. 

The  perfect  manner  in  which  the  branches  arranged 
themselves,  creeping  like  rootlets  over  every  inequality 
of  the  surface  and  into  any  deep  crevice,  is  a  pretty 
sight ;  for  it  is  perhaps  more  effectually  performed 
by  this  than  by  any  other  species.  The  action  is 
certainly  more  conspicuous,  as  the  upper  surfaces  of 
the  main  stem,  as  well  as  of  every  branch  to  the 
extreme  hooks,  are  angular  and  green,  whilst  the  lower 
surfaces  are  rounded  and  purple.  I  was  led  to  infer, 
as  in  former  cases,  that  a  less  amount  of  light  guided 
these  movements  of  the  branches  of  the  tendrils. 
I  made  many  trials  with  black  and  white  cards  and 
glass  tubes  to  prove  it,  but  failed  from  various  causes  ; 
yet  these  trials  countenanced  the  belief.  As  a  tendril 
consists  of  a  leaf  split  into  numerous  segments,  there  is 
nothing  surprising  in  all  the  segments  turning  their 
upper  surfaces  towards  the  light,  as  soon  as  the  tendril 
is  caught  and  the  revolving  movement  is  arrested. 
But  this  will  not  account  for  the  whole  movement,  for 
the  segments  actually  bend  or  curve  to  the  dark  side 
besides  turning  round  on  their  axes  so  that  their  upper 
surfaces  may  face  the  light. 

When  the  Cohsea  grows  in  the  open  air,  the  "\\ind 
must  aid  the  extremely  flexible  tendrils  in  seizing  a 
support,  for  I  found  that  a  mere  breath  sufficed  to  cause 
the  extreme  branches  to  catch  hold  by  their  hooks  of 
twigs,  which  they  could  not  have  reached  by  the 
revolving  movement.  It  might  have  been  thought 
that  a  tendril,  thus  hooked  by  the  extremity  of  a  single 
branch,  could   not   have   fairly   grasped   its   support. 


Chap.  III.  POLEMONIACEiE,  111 

But  several  times  I  watched  cases  like  the  following : 
a  tendril  caught  a  thin  stick  by  the  hooks  of  one  of 
its  two  extreme  branches ;  though  thus  held  by  the 
tip,  it  still  tried  to  revolve,  bowing  itself  to  all  sides, 
and  by  this  movement  the  other  extreme  branch  soon 
caught  the  stick.  The  first  branch  then  loosed  itself, 
and,  arranging  its  hooks,  again  caught  hold.  After  a 
time,  from  the  continued  movement  of  the  tendril, 
the  hooks  of  a  third  branch  caught  hold.  No  other 
branches,  as  the  tendril  then  stood,  could  possibly 
have  touched  the  stick.  But  before  long  the  upper 
part  of  the  main  stem  began  to  contract  into  an  open 
spire.  It  thus  dragged  the  shoot  which  bore  the 
tendril  towards  the  stick ;  and  as  the  tendril  con- 
tinually tried  to  revolve,  a  fourth  branch  was  brought 
into  contact.  And  lastly,  from  the  spiral  contraction 
travelling  down  both  the  main  stem  and  the  branches, 
all  of  them,  one  after  another,  were  ultimately  brought 
into  contact  with  the  stick.  They  then  wound  them- 
selves round  it  and  round  one  another,  until  the  whole 
tendril  was  tied  together  in  an  inextricable  knot. 
The  tendrils,  though  at  first  quite  flexible,  after 
having  clasped  a  support  for  a  time,  become  more 
rigid  and  stronger  than  they  were  at  first.  Thus  the 
plant  is  secured  to  its  support  in  a  perfect  manner. 

Leguminosj]]. — Pisum  sativum. — The  common  pea 
was  the  subject  of  a  valuable  memoir  by  Dutrochet,* 
who    discovered    that    the    internodes    and    tendrils 


*  Comptes  Eendus,  torn.  xvii.  1843,  p.  989. 


112  TENDRIL-BEAUERS.  Chap.  Ill 

revolve  in  ellipses.  The  ellijDses  are  generally  very- 
narrow,  but  sometimes  approach  to  circles.  I  several 
times  observed  that  the  longer  axis  slowly  changed  its 
direction,  which  is  of  importance,  as  the  tendril  thus 
sweeps  a  wider  space.  Owing  to  this  change  of 
direction,  and  likewise  to  the  movement  of  the  stem 
towards  the  light,  the  successive  irregular  ellipses 
generally  form  an  irregular  spire.  I  have  thought  it 
worth  while  to  annex  a  tracing  of  the  course  pursued 
by  the  upper  internode  (the  movement  of  the  tendril 
being  neglected)  of  a  young  phxnt  from  8.40  a.m.  to  9.15 
P.M.  The  course  was  traced  on  a  hemispherical  glass 
placed  over  the  plant,  and  the  dots  with  figures  give 
the  hours  of  observation ;  each  dot  being  joined  by  a 
straight  line.  No  doubt  all  the  lines  would  have  been 
curvilinear  if  the  course  had  been  observed  at  much 
shorter  intervals.  The  extremity  of  the  petiole,  from 
which  the  young  tendril  arose,  was  two  inches  from 
the  glass,  so  that  if  a  pencil  two  inches  in  length 
could  have  been  affixed  to  the  petiole,  it  would  have 
traced  the  annexed  figure  on  the  under  side  of  the 
glass ;  but  it  must  be  remembered  that  the  figure  is 
reduced  by  one-half.  Neglecting  the  first  great 
sweep  towards  the  light  from  the  figure  1  to  2,  the 
end  of  the  petiole  swept  a  space  4  inches  across  in  one 
direction,  and  3  inches  in  another.  As  a  full-grown 
tendril  is  considerably  above  two  inches  in  length,  and 
as  the  tendril  itself  bends  and  revolves  in  harmony 
with  the  internode,  a  considerably  wider  space  is  swept 
than  is  here  represented  on  a  reduced  scale.   Dutrochet 


Chap.  III. 


LEGUMINOS^. 


113 


observed  the  completion  of  an  ellipse  in  1  hr.  20  m. ; 
and  I  saw  one  completed  in  1  hr.  30  m.     The  direction 
followed  is  variable,  either  with  or  against  the  sun. 
Dutrochet  asserts  that  the   petioles  of  the  leaves 


Side  of  room  with  window. 

Fig.  6. 

niagrara  showing  the  movement  of  the  upper  internode  of  the  common  Pea,  traced  on 
a  hemispherical  glass,  and  transferred  to  paper;  reduced  one-half  in  size.  (Aug.  1st.) 


No. 


No. 


8  46  A.M. 

9  . 

10  0  „ 

10  . 

11  0  „ 

11  . 

11  37  „ 

12  . 

12  7  P.M. 

13  . 

12  30  „ 

14  . 

]  0  „ 

15  . 

1  30  „ 

H.  M. 

No. 

H.  M. 

1  55  P.M. 

16  .  . 

.  5  25  P.M 

2  25  „ 

17  .  . 

.  5  50  „ 

3  0  „ 

18  .  . 

.  6  25  „ 

3  30  „ 

19  .  . 

.70,, 

3  48  „ 

20  .   . 

.  7  45  „ 

4  40  „ 

21  .   . 

.  8  30  „ 

5  5  „ 

22  .   . 

.  9  15  „ 

spontaneously  revolve,  as  well  as  the  young  inter- 
nodes  and  tendrils;   but  he   does  not  say  that  he 
6 


114  TENDEIL-BEAEEES.  Chap.  III. 

secured  the  intern  odes ;  when  this  was  done,  I  could 
never  detect  any  movement  in  the  petiole,  except  to 
and  from  the  light. 

The  tendrils,  on  the  other  hand,  when  the  internodes 
and  petioles  are  secured,  describe  irregular  spires  or 
regular  ellipses,  exactly  like  those  made  by  the  inter- 
nodes. A  young  tendril,  only  1|  inch  in  length, 
revolved.  Dutrochet  has  shown  that  when  a  plant  is 
placed  in  a  room,  so  that  the  light  enters  laterally,  the 
internodes  travel  much  quicker  to  the  light  than  from 
it :  on  the  other  hand,  he  asserts  that  the  tendril  itself 
moves  from  the  light  towards  the  dark  side  of  the 
room.  With  due  deference  to  this  great  observer,  I 
think  he  was  mistaken,  owing  to  his  not  having 
secured  the  internodes.  I  took  a  young  plant  with 
highly  sensitive  tendrils,  and  tied  the  petiole  so  that 
the  tendril  alone  could  move ;  it  completed  a  perfect 
ellipse  in  1  hr.  30  m. ;  I  then  turned  the  plant  partly 
round,  but  this  made  no  change  in  the  direction 
of  the  succeeding  ellipse.  The  next  day  I  watched  a 
plant  similarly  secured  until  the  tendril  (which  was 
highly  sensitive)  made  an  ellipse  in  a  line  exactly  to 
and  from  the  light ;  the  movement  was  so  great  that 
the  tendril  at  the  two  ends  of  its  elliptical  course 
bent  itself  a  little  beneath  the  horizon,  thus  travelling 
more  than  180  degrees;  but  the  curvature  was  fully 
as  great  towards  the  light  as  towards  the  dark  side 
of  the  room.  I  believe  Dutrochet  was  misled  by  not 
having  secured  the  internodes,  and  by  having  observed 
a  plant  of  which  the  internodes  and  tendrils  no  longer 


Chap.  III.  LEGUMIXOS^.  115 

curved  in  harmony  togetlier,  owing  to  inequality  of 
age. 

Dutrochet  made  no  .observations  on  the  sensitiveness 
of  the  tendrils.  These,  whilst  young  and  about  an  inch 
in  length  with  the  leaflets  on  the  petiole  only  partially 
expanded,  are  highly  sensitive;  a  single  light  touch 
with  a  twig  on  the  inferior  or  concave  surface  near  the 
tip  caused'  them  to  bend  quickly,  as  did  occasionally 
a  loop  of  thread  weighing  one-seventh  of  a  grain 
(9*25  mg.).  The  upper  or  convex  surface  is  barely  or 
not  at  all  sensitive.  Tendrils,  after  bending  from  a 
touch,  straighten  themselves  in  about  two  hours,  and 
are  then  ready  to  act  again.  As  soon  as  they  begin 
to  grow  old,  the  extremities  of  their  two  or  three  pairs 
of  branches  become  hooked,  and  they  then  appear  to 
form  an  excellent  grappling  instrument ;  but  this  is 
not  the  case.  For  at  this  period  they  have  generally 
quite  lost  their  sensitiveness ;  and  when  hooked  on  to 
twigs,  some  were  not  at  all  affected,  and  others  required 
from  18  hrs.  to  24  hrs.  before  clasping  such  twigs ; 
nevertheless,  they  were  able  to  utilise  the  last  vestige 
of  irritability  owing  to  their  extremities  being  hooked. 
Ultimately  the  lateral  branches  contract  spirally,  but 
not  the  middle  or  main  stem. 

Laihijrus  aphaca. — This  plant  is  destitute  of  leaves, 
except  during  a  very  early  age,  these  being  replaced 
by  tendrils,  and  the  leaves  themselves  by  large  stipules. 
It  might  therefore  have  been  expected  that  the  ten- 
drils would  have  been  highly  organized,  but  this  is 
not   so.      They  are  moderately   long,  thiu,   and   un- 


116  TENDKIL-BEAEERS.  Chap.  Ill, 

branched,  with  their  tips  slightly  curved.  Whilst 
young  they  are  sensitive  on  all  sides,  but  chiefly  on 
the  concave  side  of  the  extremity.  They  have  no 
spontaneous  revolving  power,  but  are  at  first  inclined 
upwards  at  an  angle  of  about  45^,  then  move  into  a 
horizontal  position,  and  ultimately  bend  downwards. 
The  young  internodes,  on  the  other  hand,  revolve  in 
ellipses,  and  carry  with  them  the  tendrils.  Two 
ellipses  were  completed,  each  in  nearly  5  hrs.;  their 
longer  axes  were  directed  at  about  an  angle  of  45° 
to  the  axis  of  the  previously  made  ellipse. 

Lathyrus  grandijlorus. — The  plants  observed  were 
young  and  not  growing  vigorously,  yet  sufficiently  so, 
I  think,  for  my  observations  to  be  trusted.  If  so,  we 
have  the  rare  case  of  neither  internodes  nor  tendrils 
revolving.  The  tendrils  of  vigorous  plants  are  above 
4  inches  in  length,  and  are  often  twice  divided  into 
three  branches ;  the  tips  are  curved  and  are  sensitive 
on  their  concave  sides ;  the  lower  part  of  the  central 
stem  is  hardly  at  all  sensitive.  Hence  this  plant 
appears  to  climb  simply  by  its  tendrils  being  brought, 
through  the  growth  of  the  stem,  or  more  efiiciently 
by  the  wind,  into  contact  with  surrounding  objects, 
which  they  then  clasp.  I  may  add  that  the  tendrils, 
or  the  internodes,  or  both,  of  Vicia  sativa  revolve. 

Composite.  —  Mutisia  clematis.  —  The  immense 
family  of  the  Compositse-  is  well  known  to  include 
very  few  climbing  plants.  We  have  seen  in  the  Table 
in  the  first  chapter  that  Mikania  scandens  is  a  re- 
gular twiner,  and  F.  Miiller  informs  me  that  in  S. 


Chap.  III.  COMPOSITE.  117 

Brazil  there  is  another  species  which  is  a  leaf-climber. 
Mutisia  is  the  only  genus  in  the  family,  as  far  as 
I  can  learn,  which  bears  tendrils :  it  is  therefore 
interesting  to  find  that  these,  though  rather  less 
metamorphosed  from  their  primordial  foliar  condition 
than  are  most  other  tendrils,  yet  display  all  the 
ordinary  characteristic  movements, '  both  those  that 
are  spontaneous  and  those  which  are  excited  by  con- 
tact. 

The  long  leaf  bears  seven  or  eight  alternate  leaflets, 
and  terminates  in  a  tendril  which,  in  a  plant  of  con- 
siderable size,  was  5  inches  in  length.  It  consists 
generally  of  three  branches ;  and  these,  although 
much  elongated,  evidently  represent  the  petioles  and 
midribs  of  three  leaflets;  for  they  closely  resemble 
the  same  parts  in  an  ordinary  leaf,  in  being  rectangular 
on  the  upper  surface,  furrowed,  and  edged  with  green. 
Moreover,  the  green  edging  of  the  tendrils  of  young 
plants  sometimes  expands  into  a  narrow  lamina  or 
blade.  Each  branch  is  curved  a  little  downwards,  and 
is  slightly  hooked  at  the  extremity. 

A  young  upper  internode  revolved,  judging  from 
three  revolutions,  at  an  average  rate  of  1  hr.  38  m. ;  it 
swept  ellipses  with  the  longer  axes  directed  at  right 
angles  to  one  another ;  but  the  plant,  apparently, 
cannot  twine.  The  petioles  and  the  tendrils  are  both 
in  constant  movement.  But  their  movement  is  slower 
and  much  less  regularly  elliptical  than  that  of  the 
internodes.  They  appear  to  be  much  affected  by  the 
light,  for  the  whole  leaf  usually  sinks  down  during  the 


118  TENDETL-BEAEEES.  Chap.  III. 

night  and  rises  during  the  day,  moving,  also,  during 
the  day  in  a  crooked  course  to  the  west.  The  tip  of 
the  tendril  is  highly  sensitive  on  the  lower  surface  ; 
and  one  which  was  just  touched  with  a  twig  became 
perceptibly  curved  in  3  m.,  and  another  in  5  m. ;  the 
upper  surface  is  not  at  all  sensitive  ;  the  sides  are 
moderately  sensitive,  so  that  two  branches  which  were 
rubbed  on  their  inner  sides  converged  and  crossed  each 
other.  The  petiole  of  the  leaf  and  the  lower  parts  of 
the  tendril,  halfvvay  between  the  upper  leaflet  and  the 
lowest  branch,  are  not  sensitive.  A  tendril  after  curling 
from  a  touch  became  straight  again  in  about  6  hrs.,  and 
was  ready  to  re-act ;  but  one  that  had  been  so  roughly 
rubbed  as  to  have  coiled  into  a  helix  did  not  become 
perfectly  straight  until  after  13  hrs.  The  tendrils  re- 
tain their  sensibility  to  an  unusually  late  age  ;  for  one 
borne  by  a  leaf  with  five  or  six  fully  developed  leaves 
■  above,  was  still  active.  If  a  tendril  catches  nothing, 
after  a  considerable  interval  of  time  the  tips  of  the 
branches  curl  a  little  inwards ;  but  if  it  clasps  some 
object,  the  whole  contracts  spirally. 

SMiLACEiE. — Smilax  aspera,  var.  maculata. — Aug. 
St.-Hilaire  *  considers  that  the  tendrils,  which  rise  in 
pairs  from  the  petiole,  are  modified  lateral  leaflets ; 
but  Mohl  (p.  41)  ranks  them  as  modified  stipules. 
These  tendrils  are  from  1^  to  1|  inches  in  length,  are 
thin,  and  have  slightly  curved,  pointed  extremities. 
They  diverge  a  little  from  each  other,  and  stand  at 
first  nearly  upright.     "When  lightly  rubbed  on  either 

*  '  Le9ons  de  Botanique,'  &c.,  1841,  p.  170. 


CiIAl>.  III. 


SMILACE^, 


119 


side,  they  slowly  bend  to  that  side,  and  subsequently 
become  straight  again.  The  back  or  convex  '  side 
when  placed  in  contact  with  a  stick  became  jUst  per- 
ceptibly curved  in  1  hr.  20  m.,  but  did  not  completely 


Fig.  7. 
Smilax  aspera. 

surround  it  until  48  hrs.  had  elapsed ;  the  concave  side 
of  another  became  considerably  curved  in  2  hrs.  and 
clasped  a  stick  in  5  hrs.  As  the  pairs  of  tendrils  grow 
old,  one  tendril  diverges  more  and  more  from  the 
other,  and  both  slowly  bend  backwards  and  downwards, 
so  that  after  a  tiine  they  project  on  the  opposite  side 


120  TENDRIL-BEAKEES.  Chap.  III. 

of  the  seem  to  that  from  which  they  arise.  They  then 
still  retain  their  sensitiveness,  and  can  clasp  a  support 
placed  heliind  the  stem.  Owing  to  this  power,  the 
plant  is  able  to  ascend  a  thin,  upright  stick.  Ulti- 
mately the  two  tendrils  belonging  to  the  same  petiole, 
if  they  do  not  come  into  contact  with  any  object, 
loosely  cross  each  other  behind  the  stem,  as  at  B,  in 
iig.  7.  This  movement  of  the  tendrils  towards  and 
round  the  stem  is,  to  a  certain  extent,  guided  by  their 
avoidance  of  the  light ;  for  when  a  plant  stood  so  that 
one  of  the  two  tendrils  was  compelled  in  thus  slowly 
moving  to  travel  towards  the  light,  and  the  other  from 
the  light,  the  latter  always  moved,  as  I  repeatedly 
observed,  more  quickly  than  its  fellow.  The  tendrils 
do  not  contract  spirally  in  any  case.  Their  chance 
of  finding  a  support  depends  on  the  growth  of  the 
plant,  on  the  wind,  and  on  their  own  slow  backward 
and  downward  movement,  which,  as  we  have  just  seen, 
is  guided,  to  a  certain  extent,  by  the  avoidance  of  the 
light ;  for  neither  the  internodes  nor  the  tendrils  have 
any  proper  revolving  movement.  From  this  latter 
circumstance,  from  the  slow  movements  of  the  tendrils 
after,  contact  (though  their  sensitiveness  is  retained  for 
an  unusual  length  of  time),  from  their  simple  structure 
and  shortness,  this  plant  is  a  less  perfect  climber  than 
any  other  tendril-bearing  species  observed  by  me.  The 
plant  whilst  young  and  only  a  few  inches  in  height, 
does  not  produce  any  tendrils ;  and  considering  that 
it  grows  to  only  about  8  feet  in  height,  that  the  stem 
is  zigzag  and  is  furnished,  as  well  as  'the  petfoles,  with 


Chap.  III.  FUMARIACE^.  121 

spiues,  it  is  surprising  that  it  should  be  provided  with 
tendrils,  comparatively  inefficient  though  these  are. 
The  plant  might  have  been  left,  one  would  have 
thought,  to  climb  by  the  aid  of  its  spines  alone,  like 
our  brambles.  As,  however,  it  belongs  to  a  genus, 
some  of  the  species  of  which  are  furnished  with  much 
longer  tendrils,  we  may  suspect  that  it  possesses  these 
organs  solely  from  being  descended  from  progenitors 
more  highly  organized  in  this  respect. 

FuMARiACEiE. — Corydolis  claviculata. — According  to 
Mohl  (p.  43),  the  extremities  of  the  branched  stem, 
as  well  as  the  leaves,  are  converted  into  tendrils. 
In  the  specimens  examined  by  me  all  the  tendrils  were 
certainly  foliar,  and  it  is  hardly  credible  that  the  same 
plant  should  produce  tendrils  of  a  widely  diiferent 
homological  nature.  Nevertheless,  from  this  state- 
ment by  Mohl,  I  have  ranked  this  species  amongst  the 
tendril-bearers ;  if  classed  exclusively  by  its  foliar 
tendrils,  it  would  be  doubtful  whether  it  ought  not  to 
have  been  placed  amongst  the  leaf-climbers,  with  its 
allies,  Fumaria  and  Adlumia.  A  large  majority  of  its 
so-called  tendrils  still  bear  leaflets,  though  excessively 
reduced  in  size ;  but  some  few  of  them  may  properly 
be  designated  as  tendrils,  for  they  are  completely 
•destitute  of  laminae  or  blades.  Consequently,  we  here 
behold  a  plant  in  an  actual  state  of  transition  from  a  leaf- 
climber  to  a  tendi'il-bearer.  Whilst  the  plant  is  rather 
young,  only  the  outer  leaves,  but  when  full-grown  all 
the  leaves,  have  their  extremities  converted  into  more 
or  less  perfect  tendrils.     I  have  examined  specimens 


122  TENDPJL-BEAREES.  Chap.  III. 

from  one  locality  alone,  viz.  Hampshire ;  and  it  is  not 
improbable  that  plants  growing  under  different  condi- 
tions might  haye  their  leaves  a  little  more  or  less 
changed  into  true  tendrils. 

Whilst  the  plant  is  quite  young,  the  first-formed 
letives  are  not  modified  in  any  way,  but  those  next 
formed  have  their  terminal  leaflets  reduced  in  size, 
and  soon  all  the  leaves  assume  the  structure  repre- 
sented in  the  following  drawing.  This  leaf  bore  nine 
leaflets ;  the  lower  one^  being  much  subdivided.  The 
terminal  portion '  of  the  petiole,  about  1^  inch  in 
length  (above  the  leaflet  /),  is  thinner  and  more 
elongated  than  the  lower  part,  and  may  be  considered 
as  the  tendril.  The  leaflets  borne  by  this  part  are 
greatly  reduced  in  size,  being,  on  an  average,  about 
the  tenth  of  an  inch  in  length  and  very  narrow ;  one 
small  leaflet  measured  one-twelfth  of  an  inch  in 
length  and  one-seventy-fifth  in  breadth  (2-116  mm.  and 
•339  mm.),  so  that  it  was  almost  microscopically  minute. 
All  the  reduced  leaflets  have  branching  nerves,  and 
terminate  in  little  spines,  like  those  of  the  fully  de- 
veloped leaflets.  Every  gradation  could  be  traced, 
until  we  come  to  branchlets  (as  a  and  d  in  the  figure) 
which  show  no  vestige  of  a  lamina  or  blade.  Occasion- 
ally all  the  terminal  branchlets  of  the  petiole  are  in 
this  condition,  and  we  then  have  a  true  tendril. 

The  several  terminal  branches  of  the  petiole  bearing 
the  much  reduced  leaflets  (a,  h,  c,  d)  are  highly 
sensitive,  for  a  loop  of  thread  weighing  only  the  one- 
sixteenth  of  a  grain  (4*05  mg.)  caused  them  to  become 


Chap.  III. 


FUMARIACEJi!. 


123 


greatly  curved  in  under  4  ]irs.  When  the  loop  was 
removed,  the  petioles  straightened  themselves  in  about 
the  same  time.  The  petiole  (e)  was  rather  less  sensitive ; 
and  in  another  specimen,  in  which  the  corresponding 


Fig.  8. 

Corydalis  claviculata. 
Leaf-tendril,  of  natural  size. 


petiole  bore  rather  larger  leaflets,  a  loop  of  thread 
weishino:  one-eiffhth  of  a  grain  did  not  cause  curvature 
until  18  hrs.  had  elapsed.  Loops  of  thread  weighing 
one-fourth   of  a  grain,  left   suspended  on  the  lower 


124  TENDRIL-BEAREKS.  Chap.  III. 

petioles  (/  to  I)  during  several  days,  produced  no 
effect.  Yet  the  three  petioles  /,  g,  and  h  were  not 
quite  insensible,  for  when  left  in  contact  with  a  stick 
for  a  day  or  two  they  slowly  curled  round  it.  Thus 
the  sensibility  of  the  petiole  gradually  diminishes 
from  the  tendril-like  extremity  to  the  base.  The  in- 
ternodes  of  the  stem  are  not  at  all  sensitive,  which 
makes  Mohl's  statement  that  they  are  sometimes  con- 
verted into  tendrils  the  more  surx^rising,  not  to  say 
improbable. 

The  whole  leaf,  whilst  young  and  sensitive,  stands 
almost  vertically  upwards,  as  we  have  seen  to  be  the 
case  with  many  tendrils.  It  is  in  continual  move- 
ment, and  one  that  I  observed  swept  at  an  average 
rate  of  about  2  hrs.  for  each  revolution,  large,  though 
irregular,  ellipses,  which  were  sometimes  narrow, 
sometimes  broad,  with  their  longer  axes  directed  to 
different  points  of  the  compass.  The  young  inter- 
nodes,  likewise  revolved  irregularly  in  ellipses  or 
spires ;  so  that  by  these  combined  movements  a  con- 
siderable space  was  swept  for  a  support.  If  the  terminal 
and  attenuated  portion  of  a  petiole  fails  to  seize  any 
object,  it  ultimately  bends  downwards  and  inwards, 
and  soon  loses  all  irritability  and  power  of  movement. 
This  bending  down  differs  much  in  nature  from  that 
which  occurs  with  the  extremities  of  the  young  leaves 
in  many  species  of  Clematis;  for  these,  when  thus 
bent  downwards  or  hooked,  first  acquire  their  full 
degree  of  sensitiveness. 

Dicentra   thalidrifolia. — In    this    allied   plant    the 


Chap.  m.  FUMARIACE^.  125 

metamorphosis  of  the  terminal  leaflets  is  complete, 
and  they  are  converted  into  perfect  tendrils.  Whilst 
the  plant  is  young,  the  tendrils  appear  like  modified 
branches,  and  a  distinguished  botanist  thought  that 
they  were  of  this  nature;  but  in  a  full-grown  plant 
there  can  be  no  doubt,  as  I  am  assured  by  Dr.  Hooker, 
that  they  are  modified  leaves.  When  of  full  size,  they 
are  above  5  inches  in  length ;  they  bifurcate  twice, 
thrice,  or  even  four  times;  their  extremities  are 
hooked  and  blunt.  All  the  branches  of  the  tendrils 
are  sensitive  on  all  sides,  but  the  basal  portion  of  the 
main  stem  is  only  slightly  so.  The  terminal  branches 
when  lightly  rubbed  with  a  twig  became  curved  in 
the  course  of  from  30  m.  to  42  m.,  and  straightened 
themselves  in  between  10  hrs.  and  20  hrs.  A  looj) 
of  thread  weighing  one-eighth  of  a  grain  j^lainly 
caused  the  thinner  branches  to  bend,  as  did  occasion- 
ally a  loop  weighing  one-sixteenth  of  a  grain ;  but 
this  latter  weight,  though  left  suspended,  was  not 
sufficient  to  cause  a  permanent  flexure.  The  whole 
leaf  with  its  tendril,  as  well  as  the  young  upper  inter- 
nodes,  revolves  vigorously  and  quickly,  though  irregu- 
larly, and  thus  sweeps  a  wide  space.  The  figure  traced 
on  a  bell-glass  was  either  an  irregular  spire  or  a 
zigzag  line.  The  nearest  approach  to  an  ellipse  was  an 
elongated  figure  of  8,  with  one  end  a  little  open,  and 
this  was  completed  in  1  hr.  53  m.  During  a  period 
of  6  hrs.  17  m.  another  shoot  made  a  complex  figure, 
apparently  representing  three  and  a  half  ellipses. 
AVhen  the  lower  part  of  the  petiole  bearing  the  leaflets 


126  TENDRIL-BE AEEKS.  Chap.  III. 

was    securely   fastened,   the    tendril   itseK  described 
similar  but  much  smaller  figures. 

This  species  climbs  well.  The  tendrils  after  clasp- 
ing a  stick  become  thicker  and  more  rigid ;  but  the 
blunt  hooks  do  not  turn  and  adapt  themselves  to  the 
supporting  surface,  as  is  done  in  so  perfect  a  manner 
by  some  Bignoniacese  and  Cobaea.  The  tendrils  of 
young  plants,  two  or  three  feet  in  height,  are  only 
half  the  length  of  those  borne  by  the  same  j^lant  when 
grown  taller,  and  they  do  not  contract  spirally  after 
clasping  a  support,  but  only  become  slightly  flexuous. 
Full-sized  tendrils,  on  the  other  hand,  contract  spirally, 
with  the  exception  of  the  thick  basal  portion.  Ten- 
drils which  have  caught  nothing  simply  bend  down- 
wards and  inwards,  like  the  extremities  of  the  leaves 
of  the  Conjdalis  clavieulata.  But  in  all  cases  the 
petiole  after  a  time  is  angularly  and  abruptly  bent 
downwards  like  that  of  Eccremocarpus. 


Chap.  IV.  CUCUKBITACE^.  127 


CHAPTEE  IV. 

Tendril-Beaeeks — (continued), 

CucuEBlTACEiS — Homologous  nature  of  the  tendrils — Echtnoctjstts  lohata, 
remarkable  movements  of  the  tendrils  to  avoid  seizing  the  terminal 
shoot — Tendrils  not  excited  by  contact  with  another  tendril  or  by 
drops  of  water — Undulatory  movement  of  the  extremity  of  the  tendril 
— Hanhurya,  adherent  discs — Vitac^ — Gradation  between  the 
flower-peduncles  and  tendrils  of  the  vine — Tendrils  of  the  Virginian 
Creeper  turn  from  the  light,  and,  after  contact,  develop  adhesive 
discs — Sapindace-E  — Passiflorace-s; — Passiflora  gracilis  —  Eapid 
revolving  movement  and  sensitiveness  of  the  tendrils— Not  sensitive 
to  the  contact  of  other  tendrils  or  of  drops  of  water — Spii-al  con- 
traction of  tendrils — Summary  on  the  nature  and  action  of 
tendj'ils. 

CucuKBiTACE^. — The  tendrils  in  this  family  have 
been  ranked  by  competent  judges  as  modified  leaves, 
stipules,  or  branches  ;  or  as  partly  a  leaf  and  partly 
a  branch.  De  Candolle  believes  that  the  tendrils 
differ  in  their  homological  nature  in  two  of  the  tribes.* 
From  facts  recently  adduced,  Mr.  Berkeley  thinks, 
that  Payer's  view  is  the  most  probable,  namely,  that 
the  tendril  is  "a  separate  portion  of  the  leaf  itself;" 
but  much  may  be  said  in  favour  of  the  belief  that  it 
is  a  modified  flower-peduncle.f 


*  I  am  indebted  to  Prof.  Oliver  t  *  Gardeners'  Chronicle,'  1864, 

for  information  on  this  head.     In  p.  721.     From  the  affinity  of  the 

the  Bulletin  de  la  Societe  Bota-  Cucurbitaceaetothe  Passifloracese, 

nique  de  France,  1857,  there  are  it  might     be     argued    that     the 

numerous     discussions     on      the  tendrils  of  the  former  are  modified 

nature    of  the  tendi'ils    in    this  flower-peduncles,   as   is  certainly 

family.  the  case   with   those  of  Passion- 


128  TENDEIL-BEAEEES.  Chap.  IV. 

Echinocystis  lohata. — ^Numerous  observations  were 
made  on  this  plant  (raised  from  seed  sent  me  by  Prof. 
Asa  Gray),  for  the  spontaneous  revolving  movements 
of  the  internodes  and  tendrils  were  first  observed  by 
me  in  this  case,  and  greatly  perplexed  me.  My  obser- 
vations may  now  be  much  condensed.  I  observed 
thirty-five  revolutions  of  the  internodes  and  tendrils ; 
the  slowest  rate  was  2  hrs.,  and  the  average  rate,  with 
no  great  fluctuations,  1  hr.  40  m.  Sometimes  I  tied 
the  internodes,  so  that  the  tendrils  alone  moved ;  at 
other  times  I  cut  off  the  tendrils  whilst  very  young, 
so  that  the  internodes  revolved  by  themselves ;  but 
the  rate  was  not  thus  affected.  The  course  generally 
pursued  was  with  the  sun,  but  often  in  an  opposite 
direction.  Sometimes  the  movement  during  a  short 
time  would  either  stop  or  be  reversed;  and  this 
apparently  was  due  to  interference  from  the  light, 
as,  for  instance,  when  I  placed  a  plant  close  to  a 
window.  In  one  instance,  an  old  tendril,  which  had 
nearly  ceased  revolving,  moved  in  one  direction, 
whilst  a  young  tendril  above  moved  in  an  opposite 
course.  The  two  ujDpermost  internodes  alone  revolve ; 
and  as  soon  as  the  lower  one  grows  old,  only  its  upper 
part  continues  to  move.  The  ellipses  or  circles  swept 
by  the  summits  of  the  internodes  are  about  three  inches 
in  diameter;   whilst  those   swept  by  the  tips   of  the 


flowers.    Mr.  R.  Holland  (Hard-  garden,  where  one  of  the  short 

Tvicke's  '  Science-Gossip,'  1S65,  p.  prickles     upon     the     fruit     had 

105)  states    that     "a    cucumber  grown    out   into   a  long,    curled 

grew,  a  few  years  ago  in  njy  own  tendril." 


Chap.  IV.  CUCUEBITACE^.  129 

tendrils,  are  from  15  to  16  inches  in  diameter.  During 
the  revolving  movement,  the  internodes  become 
successively  curved  to  all  points  of  the  compass ; 
in  one  part  of  their  course  they  are  often  inclined, 
together  with  the  tendrils,  at  about  45°  to  the  horizon, 
and  in  another  part  stand  vertically  up.  There  was 
something  in  the  appearance  of  the  revolving  internodes 
which  continually  gave  the  false  impression  that  their 
movement  was  due  to  the  weight  of  the  long  and 
spontaneously  revolving  tendril ;  but,  on  cutting  off  the 
latter  with  sharp  scissors,  the  top  of  the  shoot  rose  only 
a  little,  and  went  on  revolving.  This  false  appearance 
is  aj)parently  due  to  the  internodes  and  tendrils  all 
curving  and  moving  harmoniously  together. 

A  revolving  tendril,  though  inclined  during  the 
greater  part  of  its  course  at  an  angle  of  about  45°  (in 
one  case  of  only  37°)  above  the  horizon,  stiffened  and 
straightened  itself  from  tip  to  base  in  a  certain 
part  of  its  course,  thus  becoming  nearly  or  quite 
vertical.  I  witnessed  this  repeatedly  ;  and  it  occurred 
both  when  the  supporting  internodes  were  free  and 
when  they  were  tied  up ;  but  was  perhaps  most  con- 
spicuous in  the  latter  case,  or  when  the  whole  shoot 
happened  to  be  much  inclined.  The  tendril  forms  a 
very  acute  angle  with  the  projecting  extremity  of  the 
stem  or  shoot ;  and  the  stiffening  always  occurred  as 
the  tendril  approached,  and  had  to  pass  over  the  shoot 
in  its  circular  course.  If  it  had  not  possessed  and 
exercised  this  curious  power,  it  would  infallibly  have 
struck  against  the  extremity  of  the  shoot  and  been 


130  TENDEIL-BEAREKS.  Chap.  IV. 

arrested.  As  soon  as  the  tendril  with  its  three 
branches  begins  to  stiffen  itself  in  this  manner  and  to 
rise  from  an  inclined  into  a  vertical  position,  the 
revolving  motion  becomes  more  rapid ;  and  as  soon 
as  the  tendril  has  succeeded  in  passing. over  the  ex- 
tremity of  the  shoot  or  point  of  difficulty,  its  motion, 
coinciding  with  that  from  its  weight,  often  causes  it  to 
fall  into  its  previously  inclined  position  so  quicl^y, 
that  the  apex  could  be  seen  travelling  like  the  minute 
hand  of  a  gigantic  clock. 

The  tendrils  are  thin,  from  7  to  9  inches  in  length, 
with  a  pair  of  short  lateral  branches  rising  not  far 
from  the  base.  The  tip  is  slightly  and  permanently 
curved,  so  as  to  act  to  a  limited  extent  as  a  hook.  The 
concave  side  of  the  tip  is  highly  sensitive  to  a  touch ; 
but  not  so  the  convex  side,  as  was  likewise  observed 
to  be  the  case  with  other  species  of  the  family  by 
Mohl  (p.  65).  I  repeatedly  proved  this  difference  by 
lightly  rubbing  four  or  five  times  the  convex  side  of 
one  tendril,  and  only  once  or  twice  the  concave  side 
of  another  tendril,  and  the  latter  alone  curled  inwards. 
In  a  few  hours  afterwards,  when  the  tendrils  which 
had  been  rubbed  on  the  concave  side  had  straightened 
themselves,  I  reversed  the  process  of  rubbing,  and 
always  with  the  same  result.  After  touching  the 
concave  side,  the  tip  becomes  sensibly  curved  in  one  or 
two  minutes ;  and  subsequently,  if  the  touch  has  been  at 
all  rough,  it  coils  itself  into  a  helix.  But  the  helix 
will,  after  a  time,  straighten  itself,  and  be  again  ready 
to  act.     A  loop  of  thin  thread  only  one-sixteenth  of 


Chap.  IV.  CUCUEBITACE.E.  131 

a  grain  in  weight  caused  a  temporary  flexure.     The 
lower  part  was  repeatedly  rubbed  rather  roughly,  but ' 
no  curvature  ensued ;  yet  this  part  is  sensitive  to  pro- 
longed pressure,  for  when  it  came  into  contact  with  a 
stick,  it  would  slowly  wind  round  it. 

One  of  my  plants  bore  two  shoots  near  together, 
and  the  tendrils  were  repeatedly  drawn  across  one 
another,  but  it  is  a  singular  fact  that  they  did  not 
once  catch  each  other.  It  would  appear  as  if  they  had 
become  habituated  to  contact  of  this  kind,  for  the 
pressure  thus  caused  must  have  been  much  greater 
than  that  caused  by  a  loop  of  soft  thread  weighing 
only  the  one-sixteenth  of  a  grain.  I  have,  however, 
seen  several  tendrils  of  Bryonia  dioica  interlocked,  but 
they  subsequently  released  one  another.  The  tendrils 
of  the  Echinocystis  are  also  habituated  to  drops  of 
Avater  or  to  rain ;  for  artificial  rain  made  by  violently 
flirting  a  wet  brush  over  them  produced  not  the  least 
effect. 

The  revolving  movement  of  a  tendril  is  not  stopped 
by  the  curving  of  its  extremity  after  it  has  been 
touched.  When  one  of  the  lateral  branches  has  firmly 
clasped  an  object,  the  middle  branch  continues  to 
revolve.  When  a  stem  is  bent  do^vn  and  secured,  so 
that  the  tendril  depends  but  is  left  free  to  move,  its  pre- 
vious revolving  movement  is  nearly  or  quite  stopped  ; 
but  it  soon  begins  to  bend  upwards,  and  as  soon  as  it 
has  become  horizontal  the  revolving  movement  recom- 
mences. I  tried  this  four  times  ;  the  tendril  generally 
rose  to  a  horizontal  position  in  an  hour  or  an  hour  and 


132  TENDRIL-BEAKEES.  Chap.  IV. 

a  half ;  but  in  one  case,  in  which  a  tendril  depended  at 
an  angle  of  45°  beneath  the  horizon,  the  uprising  took 
two  hours ;  in  half  an  hour  afterwards  it  rose  to  23° 
above  the  horizon  and  then  recommenced  revolving. 
This  upward  movement  is  independent  of  the  action  of 
light,  for  it  occurred  twice  in  the  dark,  and  on  another 
occasion  the  light  came  in  on  one  side  alone.  The 
movement  no  doubt  is  guided  by  opposition  to  the 
force  of  gravity,  as  in  the  case  of  the  ascent  of  the 
plumules  of  germinating  seeds. 

A  tendril  does  not  long  retain  its  revolving  power  ; 
and  as  soon  as  this  is  lost,  it  bends  downwards  and 
contracts  spirally.  After  the  revolving  movement 
has  ceased,  the  tip  still  retains  for  a  short  time  its 
sensitiveness  to  contact,  but  this  can  be  of  little  or  no 
use  to  the  plant. 

Though  the  tendril  is  highly  flexible,  and  though 
the  extremity  travels,  under  favourable  circumstances, 
at  about  the  rate  of  an  inch  in  two  minutes  and  a 
quarter,  yet  its  sensitiveness  to  contact  is  so  great  that 
it  hardly  ever  fails  to  seize  a  thin  stick  placed  in  its 
path.  The  following  case  surj)rised  me  much :  I  placed 
a  thin,  smooth,  cylindrical  stick  (and  I  repeated  the 
experiment  seven  times)  so  far  from  a  tendril,  that 
its  extremity  could  only  curl  half  or  three-quarters 
round  the  stick ;  but  I  always  found  that  the  tip 
managed  in  the  course  of  a  few  hours  to  curl  twice 
or  even  thrice  round  the  stick.  I  at  first  thought 
that  this  was  due  to  rapid  growth  on  the  outside ;  but 
by  coloured  points  and  measurements  I  proved  that 


Chap.  IV.  CUCURBITACE^.  133 

there  liad  been  no  sensible  increase  of  length  within 
the  time.  When  a  stick,  flat  on  one  side,  was 
similarly  j)l^C6d,  the  tip  of  the  tendril  could  not 
curl  beyond  the  flat  surface,  but  coiled  itself  into 
a  helix,  which,  turning  to  one  side,  lay  flat  on  the 
little  flat  surface  of  wood.  In  one  instance  a  portion 
of  tendril  three-quarters  of  an  inch  in  length  was  thus 
dragged  on  to  the  flat  surface  by  the  coiling  in  of  the 
helix.  But  the  tendril  thus  acquires  a  very  insecure 
hold,  and  generally  after  a  time  slips  off.  In  one  case 
alone  the  helix  subsequently  uncoiled  itself,  and  the 
tip  then  passed  round  and  clasped  the  stick.  The 
formation  of  the  helix  on  the  flat  side  of  the  stick 
apparently  shows  us  that  the  continued  striving  of  the 
tip  to  curl  itself  closely  inwards  gives  the  force  which 
drags  the  tendril  round  a  smooth  cylindrical  stick. 
In  this  latter  case,  whilst  the  tendril  was  slowly  and 
quite  insensibly  crawling  onwards,  I  observed  several 
times  through  a  lens  that  the  whole  surface  was  not  in 
close  contact  with  the  stick ;  and  I  can  understand  the 
onward  progress  only  by  supposing  that  the  movement 
is  slightly  undulatory  or  vermicular,  and  that  the  tip 
alternately  straightens  itself  a  little  and  then  again 
curls  inwards.  It  thus  drags  itself  onwards  by  an 
insensibly  slow,  alternate  movement,  which  may  be 
compared  to  that  of  a  strong  man  suspended  by  the 
ends  of  his  fingers  to  a  horizontal  pole,  who  works  his 
fingers  onwards  until  he  can  grasp  the  pole  with  the 
palm  of  his  hand.  However  this  may  be,  the  fact  is 
certain  that  a  tendril  which  has  caught  a  round  stick 


134  TENDRIL-BEAEERS.  Chap.  IV. 

with  its  extreme  point,  can  work  itself  onwards  until 
it  has  passed  twice  or  even  thrice  round  the  stick, 
and  has  permanently  grasped  it. 

Sanhurya  Mexicana. — The  young  internodes  and 
tendrils  of  this  anomalous  member  of  the  family,  revolve 
in  the  same  manner  and  at  about  the  same  rate  as  those 
of  the  Echinocy&tis.  The  stem  does  not  twine,  but  can 
ascend  an  upright  stick  by  the  aid  of  its  tendrils. 
The  concave  tip  of  the  tendril  is  very  sensitive ;  after 
it  had  become  rapidly  coiled  into  a  ring  owing  to 
a  single  touch,  it  straightened  itself  in  50  m.  The 
tendril,  when  in  full  action,  stands  vertically  up,  with 
the  projecting  extremity  of  the  young  stem  thrown  a 
little  on  one  side,  so  as  to  be  out  of  the  way ;  but  the 
tendril  bears  on  the  inner  side,  near  its  base,  a  short 
rigid  branch,  which  projects  out  at  right  angles  like 
a  spur,  with  the  terminal  half  bowed  a  little  down- 
wards. Hence,  as  the  main  vertical  branch  revolves, 
the  spur,  from  its  position  and  rigidity,  cannot  pass 
over  the  extremity  of  the  shoot,  in  the  same  curious 
manner  as  do  the  three  branches  of  the  tendril  of  the 
Echinocysiis,  namely,  by  stiffening  themselves  at  the 
proper  point.  The  spur  is  therefore  pressed  laterally 
against  the  young  stem  in  one  part  of  the  revolving 
course,  and  thus  the  sweep  of  the  lower  part  of  the  main 
branch  is  much  restricted.  A  nice  case  of  co-adaptation 
here  comes  into  play :  in  all  the  other  tendrils  observed 
by  me,  the  several  branches  become  sensitive  at  the 
same  period  :  had  this  been  the  case  with  the  Sanhurya, 
the   inwardly   directed,  spur-like   branch,  from  being 


Chap.  IV.  CUCURBITACE^.  135 

pressed,  during  the  revolving  movement,  against  the 
projecting  end  of  the  slioot,  would  infallibly  have 
seized  it  in  a  useless  or  injurious  manner.  But  the 
main  branch  of  the  tendril,  after  revolving  for  a  time 
in  a  vertical  position,  spontaneously  bends  downwards ; 
and  in  doing  so,  raises  the  spur-like  branch,  which 
itself  also  curves  upwards ;  so  that  by  these  combined 
movements  it  rises  above  the  projecting  end  of  the 
shoot,  and  can  now  move  freely  without  touching  the 
shoot ;  and  now  it  first  becomes  sensitive. 

The  tips  of  both  branches,  when  they  come  into 
contact  with  a  stick,  grasp  it  like  any  ordinary  tendril. 
But  in  the  course  of  a  few  days,  the  lower  surface 
swells  and  becomes  developed  into  a  cellular  layer, 
which  adapts  itself  closely  to  the  wood,  and  firmly 
adheres  to  it.  This  layer  is  analogous  to  the  adhesive 
discs  formed  by  the  extremities  of  the  tendrils  of 
some  species  of  Bignonia  and  of  Ampelopsis ;  but 
in  the  Hanhurya  the  layer  is  developed  along  the 
terminal  inner  surface,  sometimes  for  a  length  of 
If  inches,  and  not  at  the  extreme  tip.  The  layer 
is  white,  whilst  the  tendril  is  green,  and  near  the 
tip  it  is  sometimes  thicker  than  the  tendril  itself;  it 
generally  spreads  a  little  beyond  the  sides  of  the 
tendril,  and  is  fringed  with  free  elongated  cells,  which 
have  enlarged  globular  or  retort-shaped  heads.  This 
cellular  layer  apparently  secretes  some  resinous  cement ; 
for  its  adhesion  to  the  wood  was  not  lessened  by  an 
immersion  of  24  hrs.  in  alcohol  or  water,  but  was  quite 
loosened  by  a  similar  immersion  in  ether  or  turpentine. 


136  TENDEIL-BEAREKS.  Chap.  IV. 

After  a  tendril  has  once  firmly  coiled  itself  round 
a  stick,  it  is  difficult  to  imagine  of  what  use  the  ad- 
hesive cellular  layer  can  be.  Owing  to  the  spiral 
contraction  which  soon  ensues,  the  tendrils  were  never 
able  to  remain,  excepting  in  one  instance,  in  contact 
with  a  thick  post  or  a  nearly  flat  surface  ;  if  they  had 
quickly  become  attached  by  means  of  the  adhesive 
layer,  this  would  evidently  have  been  of  service  to  the 
plant. 

The  tendrils  of  Bryonia  dioica,  Cucurhita  ovifera, 
and  Cucumis  sativa  are  sensitive  and  revolve.  Whether 
the  internodes  likewise  revolve  I  did  not  observe.  In 
Anguria  Warscewiczii,  the  internodes,  though  thick 
and  stiff,  revolve :  in  this  plant  the  lower  surface  of 
the  tendril,  some  time  after  clasping  a  stick,  produces 
a  coarsely  cellular  layer  or  cushion,  which  adapts  itself 
closely  to  the  wood,  like  that  formed  by  the  tendril  of 
the  Sanhunja  ;  but  it  is  not  in  the  least  adhesive.  In 
Zanonia  Indica,  which  belongs  to  a  different  tribe  of 
the  family,  the  forked  tendrils  and  the  internodes  re- 
volve in  periods  between  2  hrs.  8  m.  and  3  hrs.  35  m., 
moving  against  the  sun. 

ViTACE^. — In  this  family  and  in  the  two  following, 
namely,  the  Sapindacese  and  Passifloracese,  the  tendrils 
are  modified  flower-peduncles ;  and  are  therefore  axial 
in  their  nature.  In  this  respect  they  difier  from  all 
those  previously  described,  with  the  exception,  j)er- 
haps,  of  the  Cucurbitacese.  The  homological  nature, 
however,  of  a  tendril  seems  to  make  no  difference 
in  its  action. 


Chap.  IV. 


VITACE^. 


137 


Viiis  vinifera. — The  tendril  is  thick  and  of  great 
len^-th ;  one  from  a  vine  growing  out  of  doors  and  not 
vigorously,  was  16  inches  long.  It  consists  of  a 
peduncle  (A),  bearing  two  branches  which  diverge 
equally  from  it.  One  of  the  branches  (B)  has  a 
scale  at  its  base ;  it  is  always,  as  far  as  I  have  seen, 
longer. than  the  other  and  often  bifurcates.  The 
branches  when    rubbed  become    curved,  and   subse- 


Fig.  9. 
Tendril  of  the  Vine. 

A.  Peduncle  of  tendril.  C.  Shorter  branch. 

B.  Longer  branch,  with  a  scale  at  its  base.        D.  Petiole  of  the  opposite  leaf. 


quently  straighten  themselves.  After  a  tendril  has 
clasped  any  object  with  its  extremity,  it  contracts 
spirally ;  but  this  does  not  occur  (Palm,  p.  56)  when 
no  object  has  been  seized.  The  tendrils  move  spon- 
7 


138  TENDEIL-BEAEEES.  Chap.  IV. 

taneously  from  side  to  side ;  and  on  a  very  hot  day 
one  made  two  elliptical  revolutions,  at  an  average  rate 
of  2  hrs.  15  m.  During  these  movements  a  coloured 
line,  painted  along  the  convex  surface,  ajapeared  after 
a  time  on  one  side,  then  on  the  concave  side,  then  on 
the  opposite  side,  and  lastly  again  on  the  convex  side. 
The  two  branches  of  the  same  tendril  have  independent 
movements.  After  a  tendril  has  spontaneously  revolved 
for  a  time,  it  bends  from  the  light  towards  the  dark : 
I  do  not  state  this  on  my  own  authority,  but  on  that 
of  Mohl  and  Dutrochet.  Mohl  (p.  77)  says  that  in  a 
vine  planted  against  a  wall  the  tendrils  point  towards 
it,  and  in  a  vineyard  generally  more  or  less  to  the 
north. 

The  young  internodes  revolve  spontaneously;  but 
the  movement  is  unusually  slight.  A  shoot  faced  a 
window,  and  I  traced  its  course  on  the  glass  during 
two  perfectly  calm  and  hot  days.  On  one  of  these 
days  it  described,  in  the  course  of  ten  hours,  a  spire, 
*representing  two  and  a  half  ellipses.  I  also  placed 
a  bell-glass  over  a  young  Muscat  grape  in  the  hot- 
house, and  it  made  each  day  three  or  four  very  small 
oval  revolutions ;  the  shoot  moving  less  than  half  an 
inch  from  side  to  side.  Had  it  not  made  at  least  three 
revolutions  whilst  the  sky  was  uniformly  overcast,  I 
should  have  attributed  this  slight  degree  of  movement 
to  the  varying  action  of  the  light.  The  extremity  of 
the  stem  is  more  or  less  bent  downwards,  but  it 
never  reverses  its  curvature,  as  so  generally  occurs 
with  twining  plants. 


Chap.  IV. 


VITACEiE. 


139 


Various  authors  (Palm,  p.  55 ;  Molil,  p.  45 ;  Lindley, 
&c.)  believe  that  the  tendrils  of  the  yine  are  modified 
flower-peduncles.  I  here  give  a  drawing  (fig.  10)  of 
the  ordinary  state  of  a  young  fl.ower-stalk :  it  consists 


Fig.  10. 
Flower-stalk  of  the  Vine. 


A.  Common  Peduncle. 

B.  Flower-tendril,  with  a  scale  at  its  base. 


C.  Sub-Peduncle,  bearing  the  flower-buds. 

D.  Petiole  of  the  opposite  leaf. 


of  the  "  common  peduncle "  (A) ;  of  the  "  flower- 
tendril  "  (B),  which  is  represented  as  having  caught  a 
twig ;  and  of  the  "  sub-peduncle  "  (C)  bearing  the 
flower-buds.  The  whole  moves  spontaneously,  like  a 
true    tendril,  but   in   a  less   degree;  the  movement^ 


140  TENDKIL-BEAKERS.  Chap.  IV 

however,  is  greater  when  the  sub-peduncle  (C)  does 
not  bear  many  flower-buds.  The  common  peduncle 
(A)  has  not  the  power  of  clasping  a  support,  nor  has 
the  corresponding  part  of  a  true  tendril.  The  flower- 
tendril  (B)  is  always  longer  than  the  sub-peduncle  (C) 
and  has  a  scale  at  its  base ;  it  sometimes  bifurcates, 
and  therefore  corresponds  in  every  detail  with  the 
longer  scale-bearing  branch  (B,  fig.  9)  of  the  true 
tendril.  It  is,  however,  inclined  backwards  from  the 
sub-peduncle  (C),  or  stands  at  right  angles  with  it, 
and  is  thus  adapted  to  aid  in  carrying  the  future 
bunch  of  grapes.  When  rubbed,  it  curves  and  sub- 
sequently straightens  itself;  and  it  can,  as  is  shown  in 
the  drawing,  securely  clasp  a  support.  I  have  seen 
an  object  as  soft  as  a  young  vine-leaf  caught  by 
one. 

The  lower  and  naked  part  of  the  sub-peduncle  (C) 
is  likewise  slightly  sensitive  to  a  rub,  and  I  have  seen 
it  bent  round  a  stick  and  even  partly  round  a  leaf 
with  which  it  had  come  into  contact.  That  the  sub- 
peduncle  has  the  same  nature  as  the  corresponding 
branch  of  an  ordinary  tendril,  is  well  shown  when  it 
bears  only  a  few  flowers ;  for  in  this  case  it  becomes 
less  branched,  increases  in  length,  and  gains  both 
in  sensitiveness  and  in  the  power  of  spontaneous 
movement.  I  have  twice  seen  sub-peduncles  which 
bore  from  thirty  to  forty  flower-buds,  and  which  had 
become  considerably  elongated  and  were  completely 
wound  round  sticks,  exactly  like  true  tendrils.  The 
whole  length  of  another  sub-peduncle,  bearing  only 


Chap.  IV.  VITACEJ5.  141 

eleven  flower-buds,  quickly  became  curved  when 
slightly  rubbed;  but  even  this  scanty  number  of 
flowers  rendered  the  stalk  less  sensitive  than  the 
other  branch,  that  is,  the  flower-tendril ;  for  the  latter 
after  a  lighter  rub  became  curved  more  quickly  and 
in  a  greater  degree.  I  have  seen  a  sub-peduncle 
thickly  covered  with  flower-buds,  with  one  of  its 
higher  lateral  branchlets  bearing  from  some  cause 
only  two  buds;  and  this  one  branchlet  had  become 
much  elongated  and  had  sjDontaneously  caught  hold 
of  an  adjoining  twig ;  in  fact,  it  formed  a  little  sub- 
tendril.  The  increasing  length  of  the  sub-peduncle 
(C)  with  the  decreasing  number  of  the  flower-buds  is  a 
good  instance  of  the  law  of  compensation.  In  accord- 
ance with  this  same  principle,  the  true  tendril  as  a  whole 
is  always  longer  than  the  flower-stalk;  for  instance, 
on  the  same  plant,  the  longest  flower-stalk  (measured 
from  the  base  of  the  comtaon  peduncle  to  the  tip  of 
the  flower-tendril)  was  8^  inches  in  length,  whilst  the 
longest  tendril  was  nearly  double  this  length,  namely 
16  inches. 

The  gradations  from  the  ordinary  state  "of  a  flower- 
stalk,  as  represented  in  the  drawing  (fig.  10),  to 
that  of  a  true  tendi-il  (fig.  9)  are  complete.  We  have 
seen  that  the  sub-peduncle  (C),  whilst  still  bearing 
from  thirty  to  forty  flower-buds,  sometimes  becomes  a 
little  elongated  and  partially  assumes  all  the  characters 
of  the  corresponding  branch  of  a  true  tendril.  From 
this  state  we  can  trace  every  stage  till  we  come  to 
a   full-sized  perfect  tendril,   bearing  on  the   branch 


142  TENDEIL-BEAEEES.  Chap.  FV. 

which  corresponds  with  the  sub-peduncle  one  single 
flower-bud!  Hence  there  can  be  no  doubt  that  the 
tendril  is  a  modified  flower-peduncle. 

Another  kind  of  gradation  well  deserves  notice. 
Flower-tendrils  (B,  fig.  10)  sometimes  produce  a  few 
flower-buds.  For  instance,  on  a  vine  growing  against 
my  house,  there  were  thirteen  and  twenty-two  flower- 
buds  respectively  on  two  flower-tendrils,  which  still 
retained  their  characteristic  qualities  of  sensitiveness 
and  spontaneous  movement,  but  in  a  somewhat  lessened 
degree.  On  vines  in  hothouses,  so  many  flowers  are 
occasionally  produced  on  the  flower-tendrils  that  a 
double  bunch'of  grapes  is  the  result ;  and  this  is  techni- 
cally called  by  gardeners  a  "  cluster."  In  this  state  the 
whole  bunch  of  flowers  presents  scarcely  any  resem- 
blance to  a  tendril ;  and,  judging  from  the  facts  already 
given,  it  would  probably  possess  little  power  of  clasping 
a  support,  or  of  spontaneous  movement.  Such  flower- 
stalks  closely  resemble  in  structure  those  borne  by 
Cissus.  This  genus,  belonging  to  the  same  family  of 
the  Vitaceae,  produces  well-developed  tendrils  and 
ordinary  bunches  of  flowers ;  but  there  are  no  gradations 
between  the  two  states.  If  the  genus  Vitis  had  been 
unknown,  the  boldest  believer  in  the  modification  of 
species  would  never  have  surmised  that  the  same 
individual  plant,  at  the  same  period  of  growth, 
would  have  yielded  every  possible  gradation  between 
ordinary  flower-stalks  for  the  support  of  the  flowers 
and  fruit,  and  tendrils  used  exclusively  for  climbing. 
But  the  vine  clearly   gives  us  such  a  case;  and  it 


Chap.  IV.  VITACE^.  143 

seems  to  me  as  striking  and  curious  an  instance  of 
transition  as  can  well  be  conceived. 

Cissus  discolor. — The  young  shoots  show  no  more 
movement  than  can  be  accounted  for  by  daily  variations 
in  the  action  of  the  light.  The  tendrils,  however, 
revolve  with  much  regularity,  following  the  sun  ;  and, 
in  the  plants  observed  by  me,  swept  circles  of  about 
5  inches  in  diameter.  Five  circles  were  completed 
in  the  following  times  : — 4  hrs.  45  m.,  4  hrs.  50  m., 
4  hrs.  45  m.,  4  hrs.  30  m.,  and  5  hrs.  The  same  tendril 
continues  to  revolve  during  three  or  four  days.  The 
tendrils  are  from  3  J  to  5  inches  in  length.  They  are 
formed  of  a  long  foot-stalk,  bearing  two  short  branches, 
which  in  old  plants  again  bifurcate.  The  two  branches 
are  not  of  quite  equal  length ;  and  as  with  the  vine, 
the  longer  one  has  a  scale  at  its  base.  The  tendi-il 
stands  vertically  upwards  ;  the  extremity  of  the  shoot 
being  bent  abruptly  downwards,  and  this  position  is 
probably  of  service  to  the  plant  by  allowing  the  tendril 
to  revolve  freely  and  vertically. 

Both  branches  of  the  tendril,  whilst  young,  are 
highly  sensitive.  A  touch  with  a  pencil,  so  gentle  as 
only  just  to  move  a  tendril  borne  at  the  end  of 
a  long  flexible  shoot,,  sufficed  to  cause  it  to  become 
perceptibly  curved  in  four  or  five  minutes.  It  became 
straight  again  in  rather  above  one  hour.  A  loop  of 
soft  thread  weighing  one-seventh  of  a  grain  (9*25  mg.) 
was  thrice  tried,  and  each  time  caused  the  tendril  to 
become  curved  in  30  or  40  m.  Half  this  weight  pro- 
duced no  effect.     The  long  foot-stalk  is  much   less 


144  TENDEIL-BEAEERS.  Chap.  IV. 

sensitive,  for  a  slight  rubbing  produced  no  effect,  al- 
though prolonged  contact  with  a  stick  caused  it  to  bend. 
The  two  branches  are  sensitive  on  all  sides,  so  that  they 
converge  if  touched  on  their  inner  sides,  and  diverge 
if  touched  on  their  outer  sides.  If  a  branch  be  touched 
at  the  same  time  with  equal  force  on  opposite  sides, 
both  sides  are  equally  stimulated  and  there  is  no  move- 
ment. Before  examining  this  plant,  I  had  observed 
only  tendrils  which  are  sensitive  on  one  side  alone, 
and  these  when  lightly  pressed  between  the  finger  and 
thumb  become  curved;  but  on  thus  pinching  many 
times  the  tendrils  of  the  Cissus  no  curvature  ensued, 
and  I  falsely  inferred  at  first  that  they  were  not  at  all 
sensitive. 

Cissus  aniarcticus. — The  tendrils  on  a  young  plant 
were  thick  and  straight,  with  the  tips  a  little  curved. 
When  their  concave  surfaces  were  rubbed,  and  it  was 
necessary  to  do  this  with  some  force,  they  very  slowly 
became  curved,  and  subsequently  straight  again. 
They  are  therefore  much  less  sensitive  than  those  of 
the  last  species ;  but  they  made  two  revolutions,  fol- 
lowing the  sun,  rather  more  rapidly,  viz.,  in  3  hrs.  30  m. 
and  4  hrs.     The  internodes  do  not  revolve. 

Amjpelojjsis  Jiederaeea  (Virginian  Creeper). — The  inter- 
nodes apparently  do  not  move  more  than  can  be 
accounted  for  by  the  varying  action  of  the  light.  The 
tendrils  are  from  4  to  5  inches  in  length,  with  the  main 
stem  sending  off  several  lateral  branches,  which  have 
their  tips  curved,  as  may  be  seen  in  the  upper  figure 
(fig.  11).    They  exhibit  no  true  spontaneous  revolving 


Chap.  IV.  VITACE^.  145 

movement,  but  turn,  as  was  long  ago  observed  by 
Andrew  Knight,*  from  the  light  to  the  dark.  I  have 
seen  several  tendrils  move  in  less  than  24  hours,  through 
an  angle  of  180°  to  the  dark  side  of  a  case  in  which 
a  plant  was  placed,  but  the  movement  is  sometimes 
much  slower.  The  several  lateral  branches  often  move 
independently  of  one  another,  and  sometimes  irregu- 
larly, without  any  apparent  cause.  These  tendrils  are 
less  sensitive  to  a  touch  than  any  others  observed  by 
me.  By  gentle  but  repeated  rubbing  with  a  twig,  the 
lateral  branches,  but  not  the  main  stem,  became  in  the 
course  of  three  or  four  hours  slightly  curved ;  but 
they  seemed  to  have  hardly  any  power  of  again 
straightening  themselves.  The  tendrils  of  a  plant  which 
had  crawled  over  a  large  box-tree  clasped  several  of  the 
branches ;  but  I  have  repeatedly  seen  that  they  will 
withdraw  themselves  after  seizing  a  stick.  When  they 
meet  with  a  flat  sui-face  of  wood  or  a  wall  (and  this 
is  evidently  what  they  are  adapted  for),  they  turn 
all  their  branches  towards  it,  and,  spreading  them 
widely  apart,  bring  their  hooked  tips  laterally  into 
contact  with  it.  In  effecting  this,  the  several  branches, 
after  touching  the  surface,  often  rise  up,  place  them- 
selves in  a  new  position,  and  again  come  down  into 
contact  with  it. 

In  the  course  of  about  two  days  after  a  tendril  has 
arranged  its  branches  so  as  to  press  on  any  surface,  the 
curved   tips  swell,  become  bright  red,  and  form   on 


*  Trans.  Pliil.Soc.  1812,  p.  314. 


146  TENDRIL-BEAEEllS.  Chap.  IV. 

their  under-sides  the  well-known  little  discs  or  cushions 
with  which  they  adhere  firmly.  In  one  case  the  tips 
were  slightly  swollen  in  38  hrs.  after  coming  into 
contact  with  a  brick ;  in  another  case  they  were 
considerably  swollen  in  48  hrs.,  and  in  an  additional 
24  hrs.  were  firmly  attached  to  a  smooth  board ;  and 
lastly,  the  tips  of  a  younger  tendril  not  only  swelled 
but  became  attached  to  a  stuccoed  wall  in  42  hrs. 
These  adhesive  discs  resemble,  except  in  colour  and 
in  being  larger,  those  of  Bignonia  capreolata.  When 
they  were  developed  in  contact  with  a  ball  of  tow,  the 
fibres  were  separately  enveloped,  but  not  in  so  effective 
a  manner  as  by  B.  capreolata.  Discs  are  never  de- 
veloped, as  far  as  I  have  seen,  without  the  stimulus  of 
at  least  temporary  contact  with  some  object.*  They 
are  generally  first  formed  on  one  side  of  the  curved  tij), 
the  whole  of  which  often  becomes  so  much  changed 
in  appearance,  that  a  line  of  the  original  green  tissue 
can  be  traced  only  along  the  concave  surface.  When, 
however,  a  tendril  has  clasped  a  cylindrical  stick,  an 
irregular  rim  or  disc  is  sometimes  formed  along  the 
inner  surface  at  some  little  distance  from  the  ciu'ved 


*  Dr.  M'Nab  remarks  (Trans.  adhere  to  any  surface.    The  ten- 

Bot.    Soc.  Edinburgh,  vol  xi.   p.  drils,  therefore,  of  one  species  of 

292)   that   the  tendrils   of  Amj).  Ampelopsis  require  the   stimulus 

Veitchii  bear  small  globular  discs  of  contact  for  the  first  development 

before  they  have  come  into  contact  of  their   discs,    whilst    those    of 

with  any  object ;  and  I  have  since  another  species  do  not  need  any 

observed   the  same   fact.    These  such  stimulus.     We  have  seen  an 

discs,  however,    increase  greatly  exactly  parallel    case    with   two 

in  size,  if  they  press  against  and  species  of  Bignoniacex. 


Chat.  IV 


VITACE^.  147 


tip  ;  this  was  also  observed  (p.  71)  by  Mohl.  The  discs 
consist  of  enlarged  cells,  witli  smooth  projecting  hemi- 
spherical surfaces,  coloured  red ;  they  are  at  first  gorged 
with  fluid  (see  section  given  by  Mohl,  p.  70),  but 
ultimately  become  woody. 

As  the   discs   soon  adhere  firmly  to  such  smooth 
surfaces  as  planed  or  painted  wood,  or  to  the  polished 
leaf  of  the  ivy,  this  alone  renders   it  probable  that 
some  cement  is  secreted,  as  has  been  asserted  to  be 
the  case  (quoted   by  Mohl,  p.  71)   by  Malpighi.     I 
removed  a  number  of  discs  formed  during  the  previous 
year  from  a  stuccoed  wall,  and  left  them  during  many 
hours,  in  warm  water,  diluted  acetic  acid  and  alcohol ; 
but  the  attached  grains   of  silex  were  not  loosened. 
Immersion  in  sulphui-ic  ether  for  24  hrs.  loosened  them 
much,  but  warmed  essential  oils  (I  tried  oil  of  thyme 
and  peppermint)  completely  released  every  particle  of 
stone  in  the  coui'se  of  a  few  hom-s.   This  seems  to  prove 
that  some  resinous  cement  is  secreted.     The  quantity, 
however,  must  be  small;   for  when  a  plant  ascended 
a  thinly  whitewashed  wall,  the  discs  adhered  firmly  to 
the  whitewash ;    but  as  the  cement  never  penetrated 
the  thin  layer,  they  were  easily  withdrawn,  together 
with  little  scales  of  the  whitewash.     It  must  not  be 
supposed  that  the  attachment  is  effected  exclusively 
by  the  cement ;  for  the  cellular  outgrowth  completely 
envelopes  every  minute  and  irregular  projection,  and 
insinuates  itself  into  every  crevice. 

A  tendril  which  has  not  become  attached  to  any 
body,  does  not  contract  spirally ;  and  in  course  of  a 


148  TENDRIL-BEARERS.  Chap.  IV. 

week  or  two  shrinks  into  the  finest  thread,  withers  and 


Fig.  11. 
Ampelopsis  hederacea. 

A.  Tendril  fully  developed,  with  a  young  leaf  on  the  opposite  side  of  the  stem. 

B.  Older  tendril,  several  weeks  after  its  attachment  to  a  wall,  with  the  branches 
thickened  and  spirally  contracted,  and  with  the  extremities  developed  into  discs. 
The  unattached  branches  of  this  tendril  have  withered  and  dropped  off. 

drops  off.      An  attached  tendril,  on  the  other  hand, 
contracts  spirally,  and  thus  becomes  highly  elastic,  so 


Ciui>.  IV.  VlTACEiE.  149 

tliat  when  the  main  foot-stalk  is  pulled  the  strain  is 
distributed  equally   between   all   the   attached   discs. 
Tor  a  few  days  after  the  attachment  of  the  discs,  the 
tendril  remains  weak  and  brittle,  but  it  rapidly  increases 
in  thickness  and  acquires  great  strength.     During  the 
following  winter  it  ceases  to  live,  but  adheres  firmly  in 
a  dead  state  both  to  its  own  stem  and  to  the  surface  of 
attachment.     In  the  accompanying  diagram  (fig.  11.) 
we  see  the  difference  between  a  tendril  (B)  some  weeks 
after  its  attachment  to  a  wall,  with  one  (A)  from  the 
same  plant  fully  grown  but   unattached.      That   the 
change  in  the  nature  of  the  tissues,  as   well  as  the 
spiral  contraction,  are  consequent  on  the  formation  of 
the  discs,  is  well  shown  by  any  lateral  branches  which 
have  not  become  attached  ;  for  these  in  a  week  or  two 
wither  and  drop  off,  in  the  same  manner  as  does  the 
whole   tendril  if  unattached.     The  gain  in  strength 
and   durability  in   a   tendril   after   its  attachment  is 
something  wonderful.     There  are  tendrils  now  adhering 
to  my  house  which  are  still  strong,  and  have  been 
exposed  to  the  weather  in  a  dead  state  for  fourteen  or 
fifteen  years.     One  single  lateral  branchlet  of  a  tendril, 
estimated  to  be  at  least  ten  years  old,  was  still  elastic 
and  supported  a  weight  of  exactly  two  pounds.     The 
whole  tendril  had  five  disc-bearing  branches  of  equal 
thickness  and  apparently  of  equal  strength ;   so  that 
after  having  been  exposed  during  ten   years   to   the 
weather,  it  would  probably  have  resisted  a  strain  of 
ten  pounds  ! 

Sapindace^. — CarcUospermum  halicacalum. — In  this 


150  TENDRIL-BEARERS.  Chap.  IV. 

family,  as  in  the  last,  the  tendrils  are  modified  flower- 
peduncles.  In  the  present  plant  the  two  lateral 
branches  of  the  main  flower-peduncle  have  been  con- 
verted into  a  pair  of  tendrils,  corresponding  with  the 
single  "  flower-tendril "  of  the  common  vine.  The 
main  peduncle  is  thin,  stiff,  and  from  3  to  4^  inches  in 
length.  Near  the  summit,  above  two  little  bracts,  it 
divides  into  three  branches.     The  middle  one  divides 


Fig.  12. 

Cardiospermum  halicacabum. 

Upper  part  of  the  flower-peduncle  with  its  two  tendrils. 

and  re-divides,  and  bears  the  flowers ;  ultimately  it 
grows  half  as  long  again  as  the  two  other  modified 
branches.  These  latter  are  the  tendrils ;  they  are  at 
first  thicker  and  longer  than  the  middle  branch,  but 
never  become  more  than  an  inch  in  length.  They 
taper  to  a  point  and  are  flattened,  with  the  lower 
clasping  sui-face  destitute  of  hairs.  At  first  they  project 
straight  up;  but  soon  diverging,  spontaneously  curl 
downwards  so  as  to  become  symmetrically  and  elegantly 
hooked,  as  represented  in  the  diagram.  They  are  now, 
whilst  the  flower-buds  are  still  small,  ready  for 
action. 


Chap.  IV.  SAPINDACE^.  151 

The  two  or  three  upper  internocles,  whilst  young, 
steadily  revolve  ;  those  on  one  plant  made  two  circles, 
against  the  course  of  the  sun,  in  3hrs.  12  m.;  in  a 
second  plant  the  same  course  was  followed,  and  the 
two  circles  were  completed  in  3  hrs.  41  m. ;  in  a  third 
plant,  the  internodes  followed  the  sun  and  made  two 
circles  in  3  hrs.  47  m.  The  average  rate  of  these  six 
revolutions  was  1  hr.  46  m.  The  stein  shows  no 
tendency  to  twine  spirally  round  a  support ;  but  the 
allied  tendril-bearing  genus  Paullinia  is  said  (Mohl,  p. 
4)  to  be  a  twiner.  The  flower-peduncles,  which  stand 
up  above  the  end  of  the  shoot,  are  carried  round  and 
round  by  the  revolving  movement  of  the  internodes  ; 
and  when  the  stem  is  securely  tied,  the  long  and 
thin  flower-peduncles  themselves  are  seen  to  be  in 
continued  and  sometimes  rapid  movement  from  side 
to  side.  They  sweep  a  wide  space,  but  only  occasion- 
ally revolve  in  a  regular  elliptical  course.  By  the 
combined  movements  of  the  internodes  and  peduncles, 
one  of  the  two  short  hooked  tendrils,  sooner  or  later, 
catches  hold  of  some  twig  or  branch,  and  then  it  curls 
round  and  securely  grasps  it.  These  tendrils  are,  how- 
ever, but  slightly  sensitive ;  for  by  rubbing  their  under 
surface  only  a  slight  movement  is  slowly  produced. 
I  hooked  a  tendril  on  to  a  twig  ;  and  in  1  hr.  45  m.  it 
was  curved  considerably  inwards ;  in  2  hrs.  30  m.  it 
formed  a  ring ;  and  in  from  5  to  6  hours  from  being 
first  hooked,  it  closely  grasped  the  stick.  A  second 
tendril  acted  at  nearly  the  same  rate ;  but  I  observed 
one  that  took  24  hours  before  it  curled  twice  round  a 


152  TENDEIL-BEATtERS.  -        Chap.  I\* 

thin  twig.  Tendrils  which  have  caught  nothing,- spon- 
taneously curl  up  to  a  close  helix  after  the  inter- 
val of  several  days.  Those  which  have  curled  round 
some  object,  soon  become  a  little  thicker  and  tougher. 
The  long  and  thin  main  peduncle,  though  sponta- 
neously moving,  is  not  sensitive  and  never  clasps  a 
sujDport.  Nor  does  it  ever  contract  spirally,*  although  a 
contraction  of  this  kind  apparently  would  have  been  of 
service  to  the  plant  in  climbing.  Nevertheless  it 
climbs  pretty  well  without  this  aid.  The  seed-capsules 
though  light,  are  of  enormous  size  (hence  its  English 
name  of  balloon-vine),  and  as  two  or  three  are  carried 
on  the  same  peduncle,  the  tendrils  rising  close  to 
them  may  be  of  service  in  preventing  their  being 
dashed  to  pieces  by  the  wind.  In  the  hothouse  the 
tendrils  served  simply  for  climbing. 

The  position  of  the  tendrils  alone  suffices  to  show 
their  homological  nature.  In  two  instances  one  of 
two  tendrils  produced  a  flower  at  its  tip  ;  this,  however, 
did  not  prevent  its  acting  properly  and  curling  round 
a  twig.  In  a  third  case  both  lateral  branches  which 
ought  to  have  been  modified  into  tendrils,  produced 
flowers  like  the  central  branch,  and  had  quite  lost 
their  tendril-structure. 

I  have  seen,  but  was  not  enabled  carefully  to  observe, 
only  one  other  climbing  Sapindaceous  plant,  namely. 


*  Fritz  Miiller  remarks  (ibid.  p.  that  the  common  peduncle  con- 

348)  that  a  related  genus,  Serjania,  tracts  spirally,  when,  as  frequently 

dififers    from    Cardiospermum    in  happens,  the  tendril  has  clasped 

bearing  only  a  single  tendril ;  and  the  plant's  own  stem. 


C'l.Ai'.   lY  PASSIFLOEACE^.  153 

FaulUnia.  It  was  not  in  flower,  yet  bore  long  forked 
tendrils.  So  that,  Paullinia,  with  respect  to  its  tendrils, 
appears  to  bear  the  same  relation  to  Cardiospermum 
that  Cissus  does  to  Vitis. 

Passiflorace^. — After  reading  the  discussion  and 
facts  given  by  Mohl  (p.  47)  on  the  nature  of  the 
tendrils  in  this  family,  no  one  can  doubt  that  they  are 
modified  flower-peduncles.  The  tendrils  and  the 
flower-peduncles  rise  close  side  by  side ;  and  my  son, 
William  E.  Darwin,  made  sketches  for  me  of  their 
earliest  state  of  development  in  the  hybrid  P.Jloribunda. 
The  two  organs  appear  at  first  as  a  single  papilla  which 
gradually  divides ;  so  that  the  tendril  appears  to  be  a 
modified  branch  of  the  flower-peduncle.  My  son  found 
one  very  young  tendril  surmounted  by  traces  of  floral 
organs,  exactly  like  those  on  the  summit  of  the  true 
flower-peduncle  at  the  same  early  age. 

Passiflora  gracilis. — This  well-named,  elegant,  annual 
species  differs  from  the  other  members  of  the  group 
observed  by  me,  in  the  young  internodes  having  the 
power  of  revolving.  It  exceeds  all  the  other  climbing 
plants  which  I  have  examined,  in  the  rapidity  of  its 
movements,  and  all  tendril-bearers  in  the  sensitiveness 
of  the  tendrils.  The  internode  which  carries  the  upper 
active  tendril  and  which  likewise  carries  one  or  two 
younger  immature  internodes,  made  three  revolutions, 
following  the  sun,  at  an  average  rate  of  1  hr.  4  m. ;  it 
then  made,  the  day  becoming  very  hot,  three  other 
revolutions  at  an  average  rate  of  between  57  and 
58  m. ;  so  that  the  average  of  all  six  revolutions  was 


154  TENDKIL-BEAKERS.  Chap.  IV. 

1  hr.  1  m.  The  apex  of  the  tendril  describes  elongated 
ellipses,  sometimes  narrow  and  sometimes  broad,  with 
their  longer  axes  inclined  in  slightly  different  direc- 
tions. The  plant  can  ascend  a  thin  upright  stick  by 
the  aid  of  its  tendrils;  but  the  stem  is  too  stiff  for  it 
to  twine  spirally  round  it,  even  when  not  interfered 
with  by  the  tendrils,  these  haying  been  successively 
pinched  off  at  an  early  age. 

When  the  stem  is  secured,  the  tendrils  are  seen  to 
revolve  in  nearly  the  same  manner  and  at  the  same 
rate  as  the  internodes.*  The  tendrils  are  very  thin, 
delicate,  and  straight,  with  the  exception  of  the  tips, 
which  are  a  little  curved ;  they  are  from  7  to  9  inches 
in  length.  A  half-grown  tendril  is  not  sensitive ;  but 
when  nearly  full-grown  they  are  extremely  sensitive. 
A  single  delicate  touch  on  the  concave  surface  of  the 
tip  soon  caused  one  to  curve ;  and  in  2  minutes  it 
formed  an  open  helix.  A  loop  of  soft  thread  weighing 
^nd  of  a  grain  (2-02  mg.)  placed  most  gently  on  the 
tip,  thrice  caused  distinct  curvature.  A  bent  bit  of 
thin  platina  wire  weighing  only  3'Qth  of  a  grain  (1*23 
mg.)  twice  produced  the  same  effect;  but  this  latter 
weight,  when  left  suspended,  did  not  sufSce  to  cause  a 
permanent  curvature.  These  trials  were  made  under 
a  bell-glass,  so  that  the  loops  of  thread  and  wire  were 


*  Prof.  Asa  Gray  informs  me  temperature  varying  from  88°-92° 

that  the  tendi-ils  of  P.  acerifolia  Ftihr.)   in  the    following    times, 

revolve  even   at  a  quicker  rate  40  m.,  45  m.,  3S|  m.,  and  46  m. 

than  those  of  P.  gracilis ;  four  One    half-revolution    was     per- 

revolutions  were  completed  (the  formed  in  15  m. 


Chap.  IV.  PASSIFLOEACE^.  155 

not  agitated  by  the  wind.  The  movement  after  a  touch 
is  very  rapid :  I  took  hold  of  the  lower  part  of  several 
tendrils,  and  then  touched  their  concave  tips  with  a 
thin  twig  and  watched  them  carefully  through  a  lens ; 
the  tips  evidently  began  to  bend  after  the  following 
intervals— 31,  25,  32, 31, 28, 39, 31,  and  30  seconds  ;  so 
that  the  movement  was  generally  perceptible  in  half  a 
minute  after  a  touch ;  but  on  one  occasion  it  was 
distinctly  visible  in  25  seconds.  One  of  the  tendrils 
which  thus  became  bent  in  31  seconds,  had  been 
touched  two  hours  previously  and  had  coiled  into  a 
helix;  so  that  in  this  interval  it  had  straightened 
itself  and  had  perfectly  recovered  its  irritability. 

To  ascertain  how  often  the  same  tendril  would 
become  curved  when  touched,  I  kept  a  plant  in  my 
study,  which  from  being  cooler  than  the  hot-house  was 
not  very  favourable  for  the  experiment.  The  extremity 
was  gently  rubbed  four  or  five  times  with  a  thin  stick, 
and  this  was  done  as  often  as  it  was  observed  to  have 
become  nearly  straight  again  after  having  been  in 
action ;  and  in  the  course  of  54  hrs.  it  answered  to  the 
stimulus  21  times,  becoming  each  time  hooked  or 
spiral.  On  the  last  occasion,  however,  the  movement 
was  very  slight,  and  soon  afterwards  permanent  spiral 
contraction  commenced.  No  trials  were  made  during 
the  night,  so  that  the  tendril  would  perhaps  have 
answered  a  greater  number  of  times  to  the  stimulus ; 
though,  on  the  other  hand,  from  having  no  rest  it 
might  have  become  exhausted  from  so  many  quickly 
repeated  efforts. 


156  TENDRIL-BEARERS.  Chap.  IV. 

I  repeated  the  experiment  made  on  the  Echinocystis, 
and  placed  several  plants  of  this  Passijlora' so  close 
together,  that  their  tendrils  were  repeatedly  dragged 
over  each  other ;  but  no  curvature  ensued.  I  likewise 
repeatedly  flirted  small  drops  of  water  from  a  brush  on 
many  tendrils,  and  syringed  others  so  violently  that 
the  whole  tendril  was  dashed  about,  but  they  never 
became  curved.  The  impact  from  the  drops  of  water 
was  felt  far  more  distinctly  on  my  hand  than  that  from 
the  loops  of  thread  (weighing  3^2^^  ^^  ^  grain)  when 
allowed  to  fall  on  it  from  a  height,  and  these  loops, 
which  caused  the  tendrils  to  become  curved,  had  been 
placed  most  gently  on  them.  Hence  it  is  clear,  that  the 
tendrils  either  have"  become  habituated  to  the  touch  of 
other  tendrils  and  drops  of  rain,  or  that  they  were  from 
the  first  rendered  sensitive  only  to  prolonged  though 
excessively  slight  pressure  of  solid  objects,  with  the 
exclusion  of  that  from  other  tendrils.  To  show  the 
difference  in  the  kind  of  sensitiveness  in  different  plants 
and  likewise  to  show  the  force  of  the  syringe  used,  I 
may  add  that  the  lightest  jet  from  it  instantly  caused 
the  leaves  of  a  Mimosa  to  close ;  whereas  the  loop  of 
thread  weighing  -3^2^^  ^^  ^  grain,  when  rolled  into  a 
ball  and  placed  gently  on  the  glands  at  the  bases  of 
the  leaflets  of  the  Mimosa,  caused  no  action. 

Passijlora  punctata. — The  internodes  do  not  move, 
but  the  tendrils  revolve  regularly.  A  half-grown  and 
very  sensitive  tendril  made  three  revolutions,  opposed 
to  the  course  of  the  sun,  in  3  hrs.  5  m.,  2  hrs.  40  m., 
and  2  hrs.  50  m. ;  perhaps  it  might  have  travelled  more 


Chap.  IV.  PASSIFLORACEiE.  157 

quickly  when  nearly  full-grown.  A  plant  was  placed 
in  front  of  a  window,  and,  as  with  twining  stems,  the 
light  accelerated  the  movement  of  the  tendril  in  one 
direction  and  retarded  it  in  the  other  ;  the  semicircle 
towards  the  light  being  performed  in  one  instance  in 
15  m.  less  time  and  in  a  second  instance  in  20  m.  less  time 
than  that  required  by  the  semicircle  towards  the  dark 
end  of  the  room.  Considering  the  extreme  tenuity  of 
these  tendrils,  the  action  of  the  light  on  them  ig 
remarkable.  The  tendrils  are  long,  and,  as  just  stated, 
very  thin,  with  the  tip  slightly  curved  or  hooked. 
The  concave  side  is  extremely  sensitive  to  a  touch — 
even  a  single  touch  causing  it  to  curl  inwards ;  it 
subsequently  straightened  itself,  and  was  again  ready 
to  act.  A  loop  of  soft  thread  weighing  j^ih  of  a  grain 
(4'625  mg.)  caused  the  extreme  tip  to  bend ;  another 
time  I  tried  to  hang  the  same  little  loop  on  an  inclined 
tendril,  but  three  times  it  slid  off;  yet  this  extra- 
ordinarily slight  degree  of  friction  sufficed  to  make  the 
tip  curl.  The  tendril,  though  so  sensitive,  does  not 
move  very  quickly  after  a  touch,  no  conspicuous  move- 
ment being  observable  until  5  or  10  m.  had  elapsed. 
The  convex  side  of  the  tip  is  not  sensitive  to  a  touch 
or  to  a  suspended  loop  of  thread.  On  one  occasion  I 
observed  a  tendril  revolving  with  the  convex  side  of 
the  tip  forwards,  and  in  consequence  it  was  not  able 
to  clasp  a  stick,  against  which  it  scraped ;  whereas 
tendrils  revolving  with  the  concave  side  forward, 
promptly  seize  any  object  in  their  path. 

Fassijiora  q^uadrangularis. — This  is  a  very  distinct 


158  TENDKIL-BEAEEES.  Chap.  IV. 

species.  The  tendrils  are  thick,  long,  and  stiff;  they 
are  sensitive  to  a  touch  only  on  the  concave  surface 
towards  the  extremity.  When  a  stick  was  j)laced  so 
that  the  middle  of  the  tendril  came  into  contact  with  it, 
no  curvature  ensued.  In  the  hothouse  a  tendril  made 
two  revolutions,  each  in  2  hrs.  22  m. ;  in  a  cool  room 
one  was  completed  in  3  hrs.,  and  a  second  in  4  hrs. 
The  internodes  do  not  revolve;  nor  do  those  of  the 
hybrid  P.  jloribunda. 

Taesonia  manicata. — Here  again  the  internodes  do 
not  revolve.  The  tendrils  are  moderately  thin  and 
long ;  one  made  a  narrow  ellipse  in  5  hrs.  20  m.,  and 
the  next  day  a  broad  ellipse  in  5  hrs.  7  m.  The 
extremity  being  lightly  rubbed  on  the  concave  surface, 
became  just  perceptibly  curved  in  7  m.,  distinctly  in 
10  m.,  and  hooked  in  20  m. 

We  have  seen  that  the  tendrils  in  the  last  three 
families,  namely,  the  Vitacese,  Sapindacese  and  Passi- 
floracese,  are  modified  flower-peduncles.  This  is  like- 
wise the  case,  according  to  De  CandoUe  (as  quoted 
by  Mohl),  with  the  tendrils  of  Brunnichia,  one  of  the 
Polygonacese.  In  two  or  three  species  of  Modecea,  one 
of  the  Papayaceae,  the  tendrils,  as  I  hear  from 
Prof.  Oliver,  occasionally  bear  flowers  and  fruit ;  so 
that  they  are  axial  in  their  nature. 

The  Spiral  Contraction  of  Tendrils. 

This  movement,  which  shortens  the  tendrils  and 
renders  them  elastic,  commences  in  half  a  day,  or  in  a 
day  or  two  after  their  extremities  have  caught  some 


Chap.  IV.  SPIRAL   CONTEACTION.  159 

object.  There  is  no  such  movement  in  any  leaf- 
climber,  with  the  exception  of  an  occasional  trace  of 
it  in  the  petioles  of  Tropxolum  trieolorum.  On  the 
other  hand,  the  tendrils  of  all  tendril-bearing  plants, 
contract  spirally  after  they  have  caught  an  object  with 
the  following  exceptions.  Firstly,  Corydalis  claviculaia, 
but  then  this  plant  might  be  called  a  leaf-climber. 
Secondly  and  thirdly,  Bignonia  unguis  with  its  close 
allies,  and  Cardiospermum ;  but  their  tendrils  are  so 
short  that  their  contraction  could  hardly  occur,  and 
would  be  quite  superfluous.  Fom-thly,  Smilax  aspera 
offers  a  more  marked  exception,  as  its  tendrils  are 
moderately  long.  The  tendrils  of  Dicentra,  whilst  the 
plant  is  young,  are  short  and  after  attachment  only 
become  slightly  flexuous ;  in  older  plants  they  are 
longer  and  then  they  contract  spirally.  I  have  seen 
no  other  exceptions  to  the  rule  that  tendrils,  after 
clasping  with  their  extremities  a  suj)port,  undergo 
spiral  contraction.  When,  however,  the  tendril  of  a 
plant  of  which  the  stem  is  immovably  fixed,  catches 
some  fixed  object,  it  does  not  contract,  simply  because 
it  cannot ;  this,  however,  rarely  occurs.  In  the 
common  Pea  the  lateral  branches  alone  contract,  and 
not  the  central  stem ;  and  with  most  plants,  such  as 
the  Vine,  Passiflora,  Bryony,  the  basal  portion  never 
forms  a  spire. 

I  have  said  that  in  Corydalis  claviculata  the  end  of 
the  leaf  or  tendril  (for  this  part  may  be  indifferently 
so  called)  does  not  contract  into  a  spire.  The 
branchlets,   however,   after    they   have   wound   round 


160  TENDRIL-BE AEERS.  Chap.  IV. 

thin  twigs,  become  deeply  sinuous  or  zigzag.  More- 
over the  whole  end  of  the  petiole  or  tendril,  if  it  seizes 
nothing,  bends  after  a  time  abruptly  downwards  and 
inwards,  showing  that  its  outer  surface  has  gone  on 
growing  after  the  inner  surface  has  ceased  to  grow. 
That  growth  is  the  chief  cause  of  the  spiral  contrac- 
tion of  tendrils  may  be  safely  admitted,  as  shown  by 
the  recent  researches  of  H.  de  Vries.  I  will,  however, 
add  one  little  fact  in  suj)port  of  this  conclusion. 

If  the  short,  nearly  straight  portion  of  an  attached 
tendril  of  Passijlora  gracilis,  (and,  as  I  believe,  of  other 
tendrils,)  between  the  opposed  spires,  be  examined,  it 
will  be  found  to  be  transversely  wrinkled  in  a  con- 
spicuous manner  on  the  outside ;  and  this  would 
naturally  follow  if  the  outer  side  had  grown  more  than 
the  inner  side,  this  part  being  at  the  same  time 
forcibly  prevented  from  becoming  curved.  So  again 
the  whole  outer  surface  of  a  spirally  wound  tendril 
becomes  wrinkled  if  it  be  pulled  straight.  Nevertheless, 
as  the  contraction  travels  from  the  extremity  of  a 
tendril,  after  it  has  been  stimulated  by  contact  with  a 
support,  down  to  the  base,  I  cannot  avoid  doubting, 
from  reasons  presently  to  be  given,  whether  the  whole 
effect  ought  to  be  attributed  to  growth.  An  unattached 
tendril  rolls  itself  up  into  a  flat  helix,  as  in  the  case  of 
Cardiospermum,  if  the  contraction  commences  at  the 
extremity  and  is  quite  regular ;  but  if  the  continued 
growth  of  the  outer  surface  is  a  little  lateral,  or  if  the 
process  begins  near  the  base,  the  terminal  portion  can- 
not be  rolled  up  within  the   basal   portion,  and   the 


Chap.  IV.  SPIRAL   CONTRACTION.  161 

tendril  then  forms  a  more  or  less  open  spire.  A 
similar  result,  follows  if  the  extremity  has  caught 
some  object,  and  is  thus  held  fast. 

The  tendrils  of  many  kinds  of  plants,  if  they  catch 
nothing,  contract  after  an  interval  of  several  days  or 
weeks  into  a  spire ;  but  in  these  cases  the  movement 
takes  place  after  the  tendril  has  lost  its  revolving 
power  and  hangs  down ;  it  has  also  then  partly  or 
wholly  lost  its  sensibility ;  so  that  this  movement  can 
be  of  no  use.  The  spiral  contraction  of  unattached 
tendrils  is  a  much  slower  process  than  that  of  attached 
ones.  Young  tendrils  which  have  caught  a  support 
and  are  spirally  contracted,  may  constantly  be  seen  on 
the  same  stem  with  the  much  older  unattached  and 
uncontracted  tendrils.  In  the  Ecliinocystis  I  have  seen  a 
tendril  with  the  two  lateral  branches  encircling  twigs 
and  contracted  into  beautiful  spires,  whilst  the  main 
branch  which  had  caught  nothing  remained  for  many 
days  straight.  In  this  plant  I  once  observed  a  main 
branch  after  it  had  caught  a  stick  become  spirally 
flexuous  in  7  hrs.,  and  spirally  contracted  in  18  hrs. 
Generally  the  tendrils  of  the  Echinocystis  begin  to 
contract  in  from  12  hrs.  to  24  hrs.  after  catching 
some  object ;  whilst  unattached  tendrils  do  not  begin 
to  contract  until  two  or  three  or  even  more  days  after 
all  revolving  movement  has  ceased.  A  full-grown 
tendril  of  Passiflora  quadrangular  is  which  had  caught 
a  stick  began  in  8  hrs.  to  contract,  and  in  21  hrs. 
formed  several  spires ;  a  younger  tendril,  only  two- 
thirds  grown,  showed  the  first  trace  of  contraction  in 


162  TENDEIL-BEAKERS.  Chap.  IV. 

two  days  after  clasping  a  stick,  and  in  two  more 
days  formed  several  spires.  It  appears,  therefore,  that 
the  contraction  does  not  begin  until  the  tendril  is 
grown  to  nearly  its  full  length.  Another  young 
tendril  of  about  the  same  age  and  length  as  the  last 
did  not  catch  any  object ;  it  acquired  its  full  length 
in  four  days ;  in  six  additional  days  it  first  became 
flexuous,  and  in  two  more  days  formed  one  com- 
plete spire.  This  first  spire  was  formed  towards  the 
basal  end,  and  the  contraction  steadily  but  slowly 
progressed  towards  the  apex ;  but  the  whole  was  not 
closely  wound  up  into  a  spire  until  21  days  had 
elapsed  from  the  first  observation,  that  is,  until  17 
days  after  the  tendril  had  grown  to  its  full  length. 

The  spiral  contraction  of  tendrils  is  quite  indepen- 
dent of  their  power  of  spontaneously  revolving,  for  it 
occurs  in  tendrils,  such  as  those  of  Lathyrus  grandi- 
fiorus  and  Ampelopsis  hederacea,  which  do  not  revolve. 
It  is  not  necessarily  related  to  the  curling  of  the  tips 
round  a  support,  as  we  see  with  the  Ampelopsis  and 
Bignonia  capreolata,  in  which  the  development  of 
adherent  discs  suffices  to  cause  spiral  contraction. 
Yet  in  some  cases  this  contraction  seems  connected 
with  the  curling  or  clasping  movement,  due  to  contact 
with  a  support ;  for  not  only  does  it  soon  follow  this 
act,  but  the  contraction  generally  begins  close  to  the 
curled  extremity,  and  travels  downwards  to  the  base. 
If,  however,  a  tendril  be  very  slack,  the  whole  length 
almost  simultaneously  becomes  at  first  flexuous  and 
then  spiral.      Again,  the  tendrils  of  some  few  plants 


Chap.  IV.  SPIRAL  CONTRACTION.  163 

never  contract  spirally  unless  they  have  first  seized 
hold  of  some  object ;  if  they  catch  nothing  they  hang 
down,  remaining  straight,  until  they  wither  and  drop 
off:  this  is  the  case  with  the  tendrils  of  Bignonia, 
which  consist  of  modified  leaves,  and  with  those  of 
three  genera  of  the  Yitacese,  which  are  modified  flower- 
peduncles.  But  in  the  great  majority  of  cases,  tendrils 
which  have  never  come  in  contact  with  any  object, 
after  a  time  contract  spirally.  All  these  facts  taken 
together,  show  that  the  act  of  clasping  a  support  and 
the  spiral  contraction  of  the  whole  length  of  the 
tendril,  are  phenomena  not  necessarily  connected. 

The  spiral  contraction  which  ensues  after  a  tendril 
has  caught  a  support  is  of  high  service  to  the  plant ; 
hence  its  almost  universal  occurrence  with  species 
belonging  to  widely  different  orders.  When  a  shoot 
is  inclined  and  its  tendril  has  caught  an  object  above, 
the  spiral  contraction  drags  up  the  shoot.  When  the 
shoot  is  upright,  the  growth  of  the  stem,  after  the 
tendrils  have  seized  some  object  above,  would  leave  it 
slack,  were  it  not  for  the  spiral  contraction  which 
draws  up  the  stem  as  it  increases  in  length.  Thus 
there  is  no  waste  of  growth,  and  the  stretched  stem 
ascends  by  the  shortest  course.  When  a  terminal 
branchlet  of  the  tendril  of  Cobaea  catches  a  stick,  we 
have  seen  how  well  the  spiral  contraction  successively 
brings  the  other  branchlets,  one  after  the  other,  into 
contact  with  the  stick,  until  the  whole  tendril  grasps 
it  in  an  inextricable  knot.  When  a  tendril  has  caught 
a   yielding  object,  this  is   sometimes   enveloped  and 


164  TENDRIL-BEARERS.  Chap.  IV. 

still  further  secured  by  the  spiral  folds,  as  I  have  seen 
with  Fassiflora  quadrangularis ;  but  this  action  is  of 
little  importance. 

A  far  more  important  service  rendered  by  the  spiral 
contraction  of  the  tendrils  is  that  they  are  thus  made 
highly  elastic.  As  before  remarked  under  Ampelopsis, 
the  strain  is  thus  distributed  equally  between  the 
several  attached  branches  ;  and  this  renders  the  whole 
far  stronger  than  it  otherwise  would  be,  as  the  branches 
cannot. break  separately.  It  is  this  elasticity  which  pro- 
tects both  branched  and  simple  tendrils  from  being  torn 
away  from  their  suj)ports  during  stormy  weather.  I 
have  more  than  once  gone  on  purpose  during  a  gale  to 
watch  a  Bryony  growing  in  an  exposed  hedge,  with 
its  tendrils  attached  to  the  surrounding  bushes;  and 
as  the  thick  and  thin  branches  were  tossed  to  and  fro 
by  the  wind,  the  tendrils,  had  they  not  been  excessively 
elastic,  would"  instantly  have  been  torn  off  and  the 
plant  thrown  prostrate.  But  as  it  was,  the  Bryony 
safely  rode  out  the  gale,  like  a  ship  with  two  anchors 
down,  and  with  a  long  range  of  cable  ahead  to  serve 
as  a  spring  as  she  surges  to  the  storm. 

When  an  unattached  tendril  contracts  spirally,  the 
spire  always  runs  in  the  same  direction  from  tip  to 
base.  A  tendril,  on  the  other  hand,  which  has  caught 
a  support  by  its  extremity,  although  the  same  side  is 
concave  from  end  to  end,  invariably  becomes  twisted 
in  one  part  in  one  direction,  and  in  another  part  in  the 
opposite  direction ;  the  oppositely  turned  spires  being 
separated  by  a  short  straight  portion.     This  curious 


Chap.  IV. 


SPIRAL  CONTRACTION. 


165 


and  symmetrical  structure  has  been  noticed  by  several 
botanists,  but  has  not  been  sufficiently  explained.*  It 
occurs  without  exception  with  all  tendrils  which  after 
catching  an  object  contract  spirally,  but  is  of  course 
most  conspicuous  in  the  longer  tendrils.  It  never 
occurs  with  uncaught  tendrils ;  and  when  this  appears 
to  have  occurred,  it  will  be  found  that  the  tendril  had 
originally  seized  some  object  and  had  afterwards  been 
torn  free.  Commonly,^  all  the  spires  at  one  end  of  an 
attached  tendril  run  in  one  direction,  and  all  those  at 


Fig.  13. 
A  caught  tendril  of  Bryonia  dioica,  spirally  contracted  in  reversed  directions. 


the  other  end  in  the  opposite  direction,  with  a  single 
short  straight  portion  in  the  middle ;  but  I  have  seen 
a  tendril  with  the  spires  alternately  turning  five  times 


*  See  M.  Isid.  Leon  in  Bull. 
Soc.  Bot.  de  France,  torn.  v.  1858, 
p.  680,  Dr.  H.  de  Vries  points 
out  (p.  306)  that  I  have  overlooked, 
in  the  first  edition  of  this  essay, 
the  following  sentence  by  Mohl : 
"After  a  tendril  has  caught  a 
Bupport,  it  begins  in  some  days  to 


wind  into  a  spire,  which,  since 
the  tendril  is  made  fast  at  both 
extremities,  must  of  necessity  be 
in  some  places  to  the  right,  in 
others  to  the  left."  But  I  am  not 
sui'prised  that  this  brief  sentence, 
without  any  further  explanation 
did  not  attract  my  attention. 


166  TENDEIL-BEAEEES.  "    Chap.  IV. 

in  opposite  directions,  with  straight  pieces  between 
them;  and  M.  Leon  has  seen  seven  or  eight  such 
alternations.  Whether  the  spires  turn  once  or  more 
than  once  in  opposite  directions,  there  are  as  many 
turns  in  the  one  direction  as  in  the  other.  For 
instance,  I  gathered  ten  attached  tendrils  of  the 
Bryony,  thg  longest  with  33,  and  the  shortest  with 
only  8  spiral  turns ;  and  the  number  of  turns  in  the 
one  direction  was  in  every  case  the  same  (within  one) 
as  in  the  opposite  direction. 

The  explanation  of  this  curious  little  fact  is  not 
difficult.  I  will  not  attempt  any  geometrical  reasoning, 
but  will  give  only  a  practical  illustration.  In  doing 
this,  I  shall  first  have  to  allude  to  a  point  which  was 
almost  passed  over  when  treating  of  Twining-plants. 
If  we  hold  in  our  left  hand  a  bundle  of  parallel  strings, 
we  can  with  our  right  hand  turn  these  round  and 
round,  thus  imitating  the  revolving  movement  of  a 
twining  plant,  and  the  strings  do  not  become  twisted. 
But  if  we  hold  at  the  same  time  a  stick  in  our 
left  hand,  in  such  a  position  that  the  strings  become 
spirally  turned  round  it,  they  will  inevitably  become 
twisted.  Hence  a  straight  coloured  line,  painted  along 
the  internodes  of  a  twining  plant  before  it  has  wound 
round  a  support,  becomes  twisted  or  spiral  after  it  has 
wound  round.  I  painted  a  red  line  on  the  straight 
internodes  of  a  Sumulus,  Mikania,  Ceropegia,  Con- 
volvulus, and  PJiaseolus,  and  saw  it  become  twisted  as 
the  plant  wound  round  a  stick.  It  is  possible  that 
the  stems  of  some  plants  by  spontaneously  turning  on 


Chap.  IV.  SPIRAL   CONTRACTION.  167 

their  own  axes,  at  the  proper  rate  and  in  the  jiroper 
direction,  might  avoid  becoming  twisted ;  but  I  have 
seen  no  such  case. 

In  the  above  illustration,  the  parallel  strings  were 
wound  round  a  stick ;  but  this  is  by  no  means  neces- 
sary, for  if  wound  into  a  hollow  coil  (as  can  be  done 
with  a  narrow  slip  of  elastic  paper)  there  is  the  same 
inevitable  twisting  of  the  axis.  When,  therefore,  a  free 
tendril  coils  itself  into  a  spire,  it  must  either  become 
twisted  along  its  whole  length  (and  this  never  occurs), 
or  the  free  extremity  must  turn  round  as  many  times 
as  there  are  spires  formed.  It  was  hardly  necessary 
to  observe  this  fact;  but  I  did  so  by  affixing  little 
paper  vanes  to  the  extreme  points  of  the  tendrils  of 
Ecliinoctjstis  and  Passijlora  quadrangularis ;  and  as 
the  tendril  contracted  itself  into  successive  spires,  the 
vane  slowly  revolved. 

We  can  now  understand  the  meaning  of  the  spires 
being  invariably  turned  in  opposite  directions,  in 
tendrils  which  from  having  caught  some  object  are 
fixed  at  both  ends.  Let  us  suppose  a  caught  tendril 
to  make  thirty  spiral  turns  all  in  the  same  direction ; 
the  inevitable  result  would  be  that  it  would  become 
twisted  thirty  times  on  its  own  axis.  This  twisting 
would  not  only  require  considerable  force,  but,  as  I 
know  by  trial,  would  burst  the  tendril  before  the  thirty 
turns  were  completed.  Such  cases  never  really  occur ; 
for,  as  already  stated,  when  a  tendril  has  caught  a 
support  and  is  spirally  contracted,  there  are  always 
as  many  turns  in  one  direction  as  in  the  other ;  so  that 


168  TENDEIL-BEAREES,  Chap.  IV. 

the  twisting  of  the  axis  in  the  one  direction  is  exactly 
compensated  by  the  twisting  in  the  opposite  direction. 
We  can  further  see  how  the  tendency  is  given  to  make 
the  later  formed  coils  opposite  to  those,  whether  turned 
to  the  right  or  to  the  left,  which  are  first  made.  Take 
a  piece  of  string,  and  let  it  hang  down  with  the  lower 
end  fixed  to  the  floor ;  then  wind  the  upper  end 
(holding  the  string  quite  loosely)  spirally  round  a  j)er- 
pendicular  pencil,  and  this  will  twist  the  lower  part  of 
the  string  ;  and  after  it  has  been  sufficiently  twisted,  it 
will  be  seen  to  curve  itself  into  an  open  spire,  with  the 
curves  running  in  an  opposite  direction  to  those  round 
the  pencil,  and  consequently  with  a  straight  piece  of 
string  between  the  opposed  spires.  In  short,  we  have 
given  to  the  string  the  regular  spiral  arrangement  of  a 
tendril  caught  at  both  ends.  The  spiral  contraction 
generally  begins  at  the  extremity'  which  has  clasped  a 
support ;  and  these  first-formed  spires  give  a  twist  to  the 
axis  of  the  tendril,  which  necessarily  inclines  the  basal 
part  into  an  opposite  spiral  curvature.  I  cannot  resist 
giving  one  other  illustration,  though  superfluous : 
when  a  haberdasher  winds  up  ribbon  for  a  customer, 
he  does  not  wind  it  into  a  single  coil ;  for,  if  he  did, 
the  ribbon  would  twist  itself  as  many  times  as  there 
were  coils ;  but  he  winds  it  into  a  figure  of  eight  on 
his  thumb  and  little  finger,  so  that  he  alternately 
takes  turns  in  opposite  directions,  and  thus  the  ribbon 
is  not  twisted.  So  it  is  with  tendrils,  with  this  sole 
difference,  that  they  take  several  consecutive  tui-ns  in 
one  direction  and  then  the  same  number  in  an  opposite 


Chap.  IV.  SUMMARY.  169 

direction;    but    in    both   cases   the    self-twisting    is 
avoided. 

Summary  on  the  Nature  and  Action  of  Tendrils. 

With  the  majority  of  tendril-bearing  plants  the  young 
internodes  revolve  in  more  or  less  broad  ellipses,  like 
those  made  by  twining  plants ;  but  the  figures  de- 
scribed, when  carefully  traced,  generally  form  irregular 
ellipsoidal  spires.  The  rate  of  revolution  varies  from 
one  to  five  hours  in  difierent  species,  and  consequently 
is  in  some  cases  more  rapid  than  with  any  twining 
plant,  and  is  never  so  slow  as  with  those  many  twiners 
which  take  more  than  five  hours  for  each  revolution. 
The  direction  is  variable  even  in  the  same  individual 
plant.  In  Passiflora,  the  internodes  of  only  one 
species  have  the  power  of  revolving.  The  Vine  is 
the  weakest  revolver  observed  by  me,  ajDparently 
exhibiting  only  a  trace  of  a  former  j)ower.  In  the 
Eccvemocarpus  the  movement  is  interrupted  by  many 
long  pauses.  Yery  few  tendril-bearing  plants  can 
spirally  twine  up  an  upright  stick.  Although  the 
power  of  twining  has  generally  been  lost,  either  from 
the  stiffness  or  shortness  of  the  internodes,  from  the  size 
of  the  leaves,  or  from  some  other  unknown  cause,  the 
revolving  movement  of  the  stem  serves  to  bring  the 
tendrils  into  contact  with  surrounding  objects. 

The  tendrils  themselves  also  spontaneously  revolve. 
The  movement  begins  whilst  the  tendril  is  young,  and 
is  at  first  slow.  The  mature  tendrils  oi  Bignonia  litf oralis 
move  much  slower  than  the   internodes.     Generally, 


170  TENDEIL-BEAllERS.  Chap.  IV. 

the  internodes  and  tendrils  reviolve  together  at  the 
same  rate ;  in  Cissus,  Cobsea,  and  most  Passifloree,  the 
tendrils.alone  revolve ;  in  other  cases,  as  with  Latliyrus 
aphaca,  only  the  internodes  move,  carrying  with  them 
the  motionless  tendrils;  and,  lastly  (and  this  is  the 
fourth  possible  case),  neither  internodes  nor  tendrils 
spontaneously  revolve,  as  with  Latliyrus  grandijlorus 
and  Aonjjelojms.  In  most  Bignonias,  Eccremocarpus, 
Mutisia,  and  the  Fumariaceae,  the  internodes,  petioles 
and  tendrils  all  move  harmoniously  together.  In 
every  case  the  conditions  of  life  must  be  favourable  in 
order  that  the  different  parts  should  act  in  a  perfect 
manner. 

Tendrils  revolve  by  the  curvature  of  their  whole 
length,  excepting  the  sensitive  extremity  and  the 
base,  which  parts  do  not  move,  or  move  but  little. 
The  movement  is  of  the  same  nature  as  that  of  the 
revolving  internodes,  and,  from  the  observations  of 
Sachs  and  H.  de  Vries,  no  doubt  is  due  to  the  same 
cause,  namely,  the  rapid  growth  of  a  longitudinal  band, 
which  travels  round  the  tendril  and  successively  bows 
each  part  to  the  oiDposite  side.  Hence,  if  a  line  be 
painted  along  that  surface  which  happens  at  the  time 
to  be  convex,,  the  line  becomes  first  lateral,  then 
concave,  then  lateral,  and  ultimately  again  convex. 
This  experiment  can  be  tried  only  on  the  thicker 
tendrils,  which  are  not  affected  by  a  thin  crust  of 
dried  paint.  The  extremities  are  often  slightly  curved 
or  hooked,  and  the  curvature  of  this  part  is  never 
reversed ;    in   this   respect  they  differ   from   the   ex- 


Chap.  IV.  SUMMARY.  171 

tremities  of  twining  shoots,  wliicli  not  only  reverse 
tlieir  curvature,  or  at  least  become  periodically  straight, 
but  curve  themselves  in  a  greater  degree  than  the 
lower  part.  In  most  other  respects  a  tendril  acts  as  if 
it  were  one  of  several  revolving  internodes,  which  all 
move  together  by  successively  bending  to  each  point 
of  the  compass.  There  is,  however,  in  many  cases  this 
unimportant  'difference,  that  the  curving  tendril  is 
separated  from  the  curving  internode  by  a  rigid 
petiole.  With  most  tendril-bearers  the  summit  of  the 
stem  or  shoot  projects  above  the  point  from  which 
the  tendril  arises ;  and  it  is  generally  bent  to  one  side, 
so  as  to  be  out  of  the  way  of  the  revolutions  swept  by 
the  tendril.  In  those  plants  in  which  the  terminal 
shoot  is  not  sufficiently  out  of  the  way,  as  we  have 
seen  with  the  Echinocystis,  as  soon  as  the  tendril 
comes  in  its  revolving  course  to  this  point,  it  stiffens 
and  straightens  itself,  and  thus  rising  vertically  up 
passes  over  the  obstacle  in  an  admirable  manner. 

All  tendrils  are  sensitive,  but  in  various  degrees,  to 
contact  with  an  object,  and  curve  towards  the  touched 
side.  With  several  plants  a  single  touch,  so  slight  as 
only  just  to  move  the  highly  flexible  tendril,  is  enough 
to  induce  curvature.  Passijlora  gracilis  possesses  the 
most  sensitive  tendrils  which  I  have  observed :  a  bit 
of  platina  wire  -^oth  of  a  grain  (1*23  mg.)  in  weight, 
gently  placed  on  the  concave  point,  caused  a  tendril 
to  become  hooked,  as  did  a  loop  of  soft,  thin  cotton 
thread  weighing  -jg^d  of  a  grain  (2'02  mg.)  With  the 
tendrils  of  several  other  plants,  loops  weighing  -^ih  of 


172  TENDRIL-BEAREES.  Chap.  IV. 

a  grain  (4"05  mg.)  sufficed.  .  The  point  of  a  tendril  of 
Passijlora  gracilis  began  to  move  distinctly  in  25 
seconds  after  a  touch,  and  in  many  cases  after  30 
seccmds.  Asa  Gray  also  saw  movement  in  the  tendrils 
of  the  Cucurbitaceous  genus,  Sicijos,  in  30  seconds. 
The  tendrils  of  some  other  plants,  when  lightly 
rubbed,  moved  in  a  few  minutes ;  with  Dicentra  in 
half-an-hour ;  with  Smilax  in  an  hour  and  a  quarter 
or  half;  and  with  Ampelopsis  still  more  slowly. 
The  curling  movement  consequent  on  a  single  touch 
continues  to  increase  for  a  considerable  time,  then 
ceases  ;  after  a  few  hours  the  tendril  uncurls  itself,  and 
is  again  ready  to  act.  When  the  tendrils  of  several 
kinds  of  plants  were  caused  to  bend  by  extremely 
light  weights  suspended  on  them,  they  seemed  to  grow 
accustomed  to  so  slight  a  stimulus,  and  straightened 
themselves,  as  if  the*  loops  had  been  removed.  It 
makes  no  difference  what  sort  of  object  a  tendril 
touches,  with  the  remarkable  exception  of  other  ten- 
drils and  drojDS  of  water,  as  was  observed  with  the 
extremely  sensitive-tendrils  of  Passijlora  gracilis  and 
of  the  Echinocystis.  I  have,  however,  seen  tendrils 
of  the  Bryony  which  had  temporarily  caught  other 
tendrils,  and  often  in  the  case  of  the  vine. 

Tendrils  of  which  the  extremities  are  permanently 
and  slightly  curved,  are  sensitive  only  on  the  concave 
surface ;  other  tendrils,  such  as  those  of  the  Cobaea 
(though  furnished  with  horny  hooks  directed  to  one  side) 
and  those  of  Cissus  discolor,  are  sensitive  on  all  sides. 
Hence  the  tendrils  of  this  latter  plant,  when  stimulated 


CUAP.  IV.  SUMMAEY.  173 

by  a  touch  of  equal  force  on  opposite  sides,  did  not 
bend.  The  inferior  and  lateral  surfaces  of  the  tendrils 
of  Midisia  are  sensitive,  but  not  the  upper  surface. 
With  branched  tendrils,  the  several  branches  act 
alike;  but  in  the  Hanhurya  the  lateral  spur-like 
branch  does  not  acquire  (for  excellent  reasons  which 
have  been  explained)  its  sensitiveness  nearly  so 
soon  as  the  main  branch.  With  most  tendrils  the 
lower  or  basal  part  is  either  not  at  all  sensitive,  or 
sensitive  only  to  prolonged  contact.  We  thus  see 
that  the  sensitiveness  of  tendrils  is  a  special  and 
localized  capacity.  It  is  quite  independent  of  the 
power  of  spontaneously  revolving ;  for  the  curling  of 
the  terminal  portion  from  a  touch  does  not  in  the  least 
interrupt  the  former  movement.  In  Bignonia  unguis 
and  its  close  allies,  the  petioles  of  the  leaves,  as  well 
as  the  tendrils,  are  sensitive  to  a  touch. 

Twining  plants  when  they  come  into  contact  with  a 
stick,  curl  round  it  invariably  in  the  direction  of  their 
revolving  movement;  but  tendrils  curl  indifferently 
to  either  side,  in  accordance  with  the  position  of  the 
stick  and  the  side  which  is  first  touched.  The  clasping 
movement  of  the  extremity  is  apparently  not  steady, 
but  undulatory  or  vermicular  in  its  nature,  as  may  be 
inferred  from  the  curious  manner  in  which  the  tendrils 
of  the  Echinocystis  slowly  crawled  round  a  smooth 
stick. 

As  with  a  few  exceptions  tendrils  spontaneously 
revolve,  it  may  be  asked, — why  have  they  been  endowed 
with  sensitiveness  ? — why,  when  they  come  into  contact 


174  TENDKIL-BEAEEES.  Chap.  IV. 

with  a  stick,  do  they  not,  like  twining  plants,  spirally 
wind  round  it  ?  One  reason  may  be  that  they  are  in 
most  cases  so  flexible  and  thin,  that  when  brought 
into  contact  with  any  object,  they  would  almost 
certainly  yield  and  be  dragged  onwards  by  the  revolv- 
ing movement.  Moreover,  the  sensitive  extremities 
have  no  revolving  power  as  far  as  I  have  observed, 
and  could  not  by  this  means  curl  round  a  support. 
With  twining  plants,  on  the  other  hand,  the  extremity 
spontaneously  bends  more  than  any  other  part;  and 
this  is  of  high  importance  for  the  ascent  of  the  plant, 
as  may  be  seen  on  a  windy  day.  It  is,  however,  possible 
that  the  slow  movement  of  the  basal  and  stifier  parts 
of  certain  tendrils,  which  wind  round  sticks  placed  in 
their  path,  may  be  analogous  to  that  of  twining  plants. 
But  I  hardly  attended  sufficiently  to  this  point,  and  it 
would  have  been  difficult  to  distinguish  between  a 
movement  due  to  extremely  dull  irritability,  from  the 
arrestment  of  the  lower  part,  whilst  the  upper  part 
continued  to  move  onwards. 

Tendrils  which  are  only  three-fom'ths  grown,  and 
perhaps  even  at  an  earlier  age,  but  not  whilst  extremely 
young,  have  the  power  of  revolving  and  of  grasping 
any  object  which  they  touch.  These  two  capacities 
are  generally  acquired  at  about  the  same  period,  and 
both  fail  when  the  tendril  is  full  grown.  But  in 
Cdbsea  and  Passijlora  punctata  the  tendrils  begin  to 
revolve  in  a  useless  manner,  before  they  have  become 
sensitive.  In  the  Echinocystis  they  retain  their 
sensitiveness  for  some  time  after  they  have  ceased  to 


CuAr.  IV.  SUMMAKY.  175 

revolve  and  after  they  have  sunk  downwards ;  in  this 
position,  even  if  they  were  able  to  seize  an  object,  such 
power  would  be  of  no  service  in  supporting  the  stem. 
It  is  a  rare  circumstance  thus  to  detect  any  super- 
fluity or  imperfection  in  the  action  of  tendrils — organs 
which  are  so  excellently  adapted  for  the  functions 
which  they  have  to  perform ;  but  we  see  that  they  are 
not  always  perfect,  and  it  would  be  rash  to  assume 
that  any  existing  tendril  has  reached  the  utmost  limit 
of  perfection. 

Some  tendrils  have  their  revolving  motion  accelerated 
or  retarded,  in  moving  to  or  from  the  light ;  others, 
as  with  the  Pea,  seem  indifferent  to  its  action ;  others 
move  steadily  from  the  light  to  the  dark,  and  this  aids 
them  in  an  important  manner  in  finding  a  support. 
For  instance,  the  tendrils  of  Bignonia  capreolata  bend 
from  the  light  to  the  dark  as  truly  as  a  wind- vane  from 
the  wind.  In  the  Eccremocarpus  the  extremities  alone 
twist  and  turn  about  so  as  to  bring  their  finer  branches 
and  hooks  into  close  contact  with  any  dark  surface,  or 
into  crevices  and  holes. 

A  short  time  after  a  tendril  has  caught  a  support, 
it  contracts  with  some  rare  exceptions  into  a  spire ; 
but  the  manner  of  contraction  and  the  several  important 
advantages  thus  gained  have  been  discussed  so  lately, 
that  nothing  need  here  be  repeated  on  the  subject. 
Tendrils  soon  after  catching  a  support  grow  much 
stronger  and  thi«^,ker,  and  sometimes  more  durable  to  a 
wonderful  degree;  and  this  shows  how  much  their 
internal  tissues  must  be  changed.     Occasionally  it  is 


17G  TENDRIL-BEAEEES.  Chap.  IV. 

the  part  which  is  wound  round  a  support  which 
chiefly  becomes  thicker  and  stronger;  I  have  seen, 
for  instance,  this  part  of  a  tendril  of  Bignonia  wqui- 
nodialis  twice  as  thick  and  rigid  as  the  free  basal  part. 
Tendrils  which  have  caught  nothing  soon  shrink  and 
wither ;  but  in  some  species  of  Bignonia  they  disarti- 
culate and  fall  off  like  leaves  in  autumn. 

Any  one  who  had  not  closely  observed  tendrils  of 
many  kinds  would  probably  infer  that  their  action  was 
uniform.  This  is  the  case  with  the  simpler  kinds, 
which  simply  curl  round  an  object  of  moderate  thick- 
ness, whatever  its  nature  may  be.*  But  the  genus 
Bignonia  shows  us  what  diversity  of  action  there  may 
be  between  the  tendrils  of  closely  allied  species.  In 
all  the  nine  species  observed  by  me,  the  young  in- 
ternodes  revolve  vigorously ;  the  tendrils  also  re- 
volve, but  in  some  of  the  species  in  a  very  feeble 
manner  ;  and  lastly  the  petioles  of  nearly  all  revolve 
though  with  unequal  power.  The  petioles  of  three  of  the 
species,  and  the  tendrils  of  all  are  sensitive  to  contact. 
In  the  first-described  species,  the  tendrils  res  mble 
in  shape  a  bird's  foot,  and  they  are  of  no  service  to  the 
stem  in  spirally  ascending  a  thin  upright  stick,  but 
they  can  seize  firm  hold  of  a  twig  or  branch.     When 


*  Sachs,  however  ('  Text-Book  adapted    to     clasp     supports    of 

ofBotany,'Eng. Translation,] 875,  different  thicknesses.    He  further 

p.  280),  has    shown   that   which  shows   that    after  a  tendril    has 

I  overlooked,  namely,   that    the  clasped  a  support  it  subsequently 

tendrils  of    different  species  are  tightens  its  hold. 


Ciur.  IV.  SUMMARY.  177 

tbe  stem  twines  round  a  somewhat  thick  stick,  a  slight 
degree  of  sensitiveness  possessed  by  the  petioles  is 
brought  into  play,  and  the  whole  leaf  together  with 
the  tendril  winds  round  it.  In  B.  unguis  the  petioles 
are  more  sensitive,  and  have  greater  power  of  move- 
ment than  those  of  the  last  species ;  they  are  able, 
together  with  the  tendrils,  to  wind  inextricably  round 
a  thin  upright  stick ;  but  the  stem  does  not  twine 
so  well.  B.  Ttveedi/ana  has  similar  powers,  but  in 
addition,  emits  aerial  roots  which  adhere  to  the  wood. 
In  B.  vemista  the  tendrils  are  converted  into  elongated 
three-pronged  grapnels,  which  move  spontaneously  in 
a  conspicuous  manner ;  the  petioles,  however,  have  lost 
their  sensitiveness.  The  stem  of  this  species  can  twine 
round  an  uj^right  stick,  and  is  aided  in  its  ascent  by 
the  tendrils  seizing  the  stick  alternately  some  way 
above  and  then  contracting  spirally.  In  B.  littoralis 
the  tendrils,  petioles,  and  internodes,  all  revolve  spon- 
taneously The  stem,  however,  cannot  twine,  but  ascends 
an  upright  stick  by  seizing  it  above  with  both  tendrils 
together,  which  then  contract  into  a  spire.  The  tips 
of  these  tendrils  become  developed  into  adhesive  discs. 
B.  Sjjeciosa  possesses  similar  powers  of  movement  as 
the  last  species,  but  it  cannot  twine  round  a  stick, 
though  it  can  ascend  by  clasping  the  stick  horizon- 
tally with  one  or  both  of  its  imbranched  tendrils. 
These  tendrils  continually  insert  their  pointed  ends 
into  minute  crevices  or  holes,  but  as  they  are  always 
withdrawn  by  the .  subsequent  spiral  contraction,  the 
habit  seems  to  us  in  our  ignorance  useless.    Lastly, 


178  TENDKIL-BEAEEES.  Chaf.  IV. 

the  stem  ofi?.  eajyreolata  ivfines  imperfectly;  themucli- 
branclied  tendrils  revolve  in  a  capricious  manner,  and 
bend  from  the  light  to  the  dark;  their  hooked  ex- 
tremities, even  whilst  immature,  crawl  into  crevices, 
and,  when  mature,  seize  any  thin  projecting  point; 
in  either  case  they  develop  adhesive  discs,  and  these 
have  the  power  of  enveloping  the  finest  fibres. 

In  the  allied  Eccremocarpus  the  internodes,  petioles, 
and  much-branched  tendrils  all  spontaneously  revolve 
together.  The  tendrils  do  not  as  a  whole  turn  from 
the  light ;  but  their  bluntly-hooked  extremities  arrange 
themselves  neatly  on  any  surface  with  which  they 
come  into  contact,  ajjparently  so  as  to  avoid  the  light. 
They  act  best  when  each  branch  seizes  a  few  thin 
stems,  like  the  culms  of  a  grass,  which  they  after- 
wards draw  together  into  a  solid  bundle  by  the  spiral 
contraction  of  all  the  branches.  In  Cobaea  the 
finely-branched  tendrils  alone  revolve;  the  branches 
terminate  in  sharp,  hard,  double,  little  hooks,  with 
both  points  directed  to  the  same  side ;  and  these  turn 
by  well-adapted  movements  to  any  object  with  which 
they  come  into  contact.  The  tips  of  the  branches 
also  crawl  into  dark  crevices  or  holes.  The  tendrils 
and  internodes  of  Ampelopsis  have  little  or  no  power 
of  revolving ;  the  tendrils  are  but  little  sensitive  to 
contact;  their  hooked  extremities  cannot  seize  thin 
objects ;  they  will  not  even  clasp  a  stick,  unless  in 
extreme  need  of  a  support;  but  they  turn  from  the 
light  to  the  dark,  and,  spreading  out  their  branches  in 
contact  with  any  nearly  flat  surface,  develop  discs. 


Chap.  IV.  SUMMARY.  179 

These  adhere  by  the  secretion  of  some  cement  to  a 
wall,  or  even  to  a  polished  surface ;  and  this  is  more 
than  the  discs  of  the  Bignonia  capreolafa  can  effect. 

The  rapid  development  of  these  adherent  discs  is 
one  of  the  most  remarkable  peculiarities  possessed  by 
any  tendrils.  We  have  seen  that  such  discs  are  formed 
by  two  species  of  Bignonia,  by  Ampelopsis,  and, 
according  to  Naudin,*  by  the  Cucurbitaceous  genus 
Peponojysis  adherens.  In  Anguria  the  lower  surface  of 
the  tendril,  after  it  has  wound  round  a  stick,  forms 
a  coarsely  cellular  layer,  which  closely  fits  the  wood, 
but  is  not  adherent ;  whilst  in  Hanburya  a  similar 
layer  is  adherent.  The  growth  of  these  cellular  out- 
growths depends,  (except  in  the  case  of  the  Ilaplolopliium 
and  of  one  species  of  Ampelopsis,)  on  the  stimulus  from 
contact.  It  is  a  singular  fact  that  three  families,  so 
widely  distinct  as  the  Bignoniaceae,  Vitaceae,  and 
Cucurbitacese,  should  possess  species  with  tendrils 
having  this  remarkable  power. 

Sachs  attributes  all  the  movements  of  tendrils  to 
rapid  growth  on  the  side  opposite  to  that  which 
becomes  concave.  These  movements  consist  of  re- 
volving nutation,  the  bending  to  and  from  the  light, 
and  in  opposition  to  gravity,  those  caused  by  a  touch, 
and  spiral  contraction.  It  is  rash  to  differ  from  so  great 
an  authority,  but  I  cannot  believe  that  one  at  least  of 


*  Annales  des  Sc.  Nat.  Bot.  4th  series,  torn.  xii.  p.  89. 


180  TENDEIL-BEAKEES.  Chap.  IV. 

these  movements — curvature  from  a  touch — is  thus 
caused.*  In  the  first  place  it  may  be  remarked  that  the 
movement  of  nutation  differs  from  that  due  to  a  touch, 
in  so  far  that  in  some  cases  the  two  powers  are  acquired 
by  the  same  tendril  at  different  periods  of  growth ; 
and  the  sensitive  part  of  the  tendril  does  not  seem 
capable  of  nutation.  One  of  my  chief  reasons  for  doubt- 
ing whether  the  curvature  from  a  touch  is  the  result 
of  growth,  is  the  extraordinary  rap'idity  of  the  move- 
ment. I  have  seen  the  extremity  of  a  tendril  of 
Passiflora  gracilis,  after  being  touched,  distinctly  bent 
in  25  seconds,  and  often  in  30  seconds ;  and  so  it  is 
with  the  thicker  tendril  of  Sicyos.  It  appears  hardly 
credible  that  their  outer  surfaces  could  have  actually 
grown  in  length,  which  implies  a  permanent  modifica- 
tion of  structure,  in  so  short  a  time.  The  growth, 
moreover,  on  this  view  must  be  considerable,  for  if  the 
touch  has  been  at  all  rough  the  extremity  is  coiled 
in  two  or  three  minutes  into  a  spire  of  several  turng. 

When  the  extreme  tip  of  the  tendril  of  Echinocystis 
caught  hold  of  a  smooth  stick,  it  coiled  itself  in  a 
few  hours  (as  described  at  p.  132)  twice  or  thrice  round 


*  It  occurred  to    me   that  the  cilis,  but  I  succeeded  only  in  ob- 

movement  of  nutation  and  that  serving  that  both  movements  were 

from  a  touch  might  be  differently  unaffected  by  exposure  for  1^  hrs. 

affected  by    anjcsthetics,    in    the  to  a  rather  large  dose  of  sulphu- 

same   manner  as  Paul   Bert  has  ric  ether.      In   this  respect  they 

shown  to  be  the   case  •with  the  present  a  wonderful  contrast  with 

Bleep-movements  of  Mimosa  and  Drosera,  owing  no  doubt  to  the 

tliose  from  a  touch.    I  tried  the  presence  of  absorbent  glands  in 

common  pea  and  Fassijlora  gra-  the  latter  plaut. 


Chap.  IV.  SUMMARY.  181 

the  stick,  apparently  by  an  undulatory  movement.  At 
first  I  attributed  this  movement  to  the  growth  of  the 
outside;  black  marks  were  therefore  made,  and  the 
interspaces  measured,  but  I  could  not  thus  detect  any 
increase  in  length.  Hence  it  seems  probable  in  this 
case  and  in  others,  that  the  curvature  of  the  tendril 
from  a  touch  depends  on  the  contraction  of  the  cells 
along  the  concave  side.  Sachs  himself  admits*  that 
"  if  the  growth  which  takes  place  in  the  entire  tendril 
"  at  the  time  of  contact  with  a  support  is  small,  a 
"  considerable  acceleration  occurs  on  the  convex  sur 
"  face,  but  in  general  there  is  no  elongation  on  the 
"  concave  surface,  or  there  may  even  be  a  contraction ; 
"  in  the  case  of  a  tendril  of  Cucurbita  this  contraction 
"  amounted  to  nearly  one-third  of  the  original  length." 
In  a  subsequent  passage  Sachs  seems  to  feel  some  diffi- 
culty in  accounting  for  this  kind  of  contraction.  It 
must  not  however  be  supposed  from  the  foregoing 
remarks  that  I  entertain  any  doubt,  after  reading  De 
Vries'  observations,  about  the  outer  and  stretched 
surfaces  of  attached  tendrils  afterwards  increasiuir  in 
length  by  growth.  Such  increase  seems  to  me  quite 
compatible  with  the  first  movement  being  independent 
of  growth.  Why  a  delicate  touch  should  cause  one 
side  of  a  tendril  to  contract  we  know  as  little  as  why, 
on  the  view  held  by  Sachs,  it  should  lead  to  extra- 
ordinarily rapid  growth  of  the  opposite  side.  The 
chief  or  sole  reason  for  the  belief  that  the  curvature  of 


'  Text-Book  of  Botany,  1875,  p.  779. 


182  TENDEIL-BEAEERS.  Chap.  IV. 

a  tendril  when  touched  is  due  to  rapid  growth,  seems  to 
be  that  tendrils  lose  their  sensitiveness  and  power  of 
movement  after  they  have  grown  to  their  full  length ; 
but  this  fact  is  intelligible,  if  we  bear  in  mind  that  all 
the  functions  of  a  tendril  are  adapted  to  drag  up  the 
terminal  growing  shoot  towards  the  light.  Of  what 
use  would  it  be,  if  an  old  and  full-grown  tendril, 
arising  from  the  lower  part  of  a  shoot,  were  to  retain 
its  power  of  clasping  a  support?  This  would  be  of 
no  use ;  and  we  have  seen  with  tendrils  so  many  in- 
stances of  close  adaptation  and  of  the  economy  of 
^eans,  that  we  may  feel  assured  that  they  would 
acquire  irritability  and  the  power  of  clasping  a  support 
at  the  proper  age  —  namely,  youth — and  would  not 
uselessly  retain  such  power  beyond  the  proper  age. 


Chap.  V.  HOOK-CLIMBERS.  183 


CHAPTEE  V. 

Hook  and  Root-Climbeks. — Concllding  Remarks. 

Plants  climbing  by  the  aid  of  books,  or  merely  scrambling  over  other 
plants — Eoot-climbers,  adhesive  matter  secreted  by  the  rootlets — 
General  conclusions  with  respect  to  climbing  plants,  and  the  stages 
of  their  development. 

Hooh-CUmhers. —  In  my  introductory  remarks,  I  stated 
that,  besides  the  two  first  great  classes  of  climbing 
plants,  namely,  those  which  twine  round  a  support, 
and  those  endowed  with  irritability  enabling  them  to 
seize  hold  of  objects  by  means  of  their  petioles  or 
tendrils,  there  are  two  other  classes,  hook-climbers  and 
root-climbers.  Many  plants,  moreover,  as  Fritz  Miiller 
has  remarked,*  climb  or  scramble  up  thickets  in  a  still 
more  simple  fashion,  without  any  special  aid,  excepting 
that  their  leading  shoots  are  generally  long  and  flexible. 
It  may,  however,  be  suspected  from  what  follows,  that 
these  shoots  in  some  cases  tend  to  avoid  the  liirht. 
The  few  hook-climbers  which  I  have  observed,  namely, 
Galium  aparine,  Buhus  australis,  and  some  climbing 


♦  Journal  of  Linn.  Soc.  vol.  ix.  plant.s  growing  beneath  other  and 

p.  348.  Professor  G.  Jaeger  has  well  taller  species  or  trees,  are  naturally 

remarked  ('  In  Sachen  Darwin's,  those  which  would  be  developt  d 

insbesondere     contra      Wigaud,'  into  climbers ;  and    such  plants, 

1874:,   p.  106)   that    it   is  highly  from  stretching  towards  the  light, 

characteristic  of  climbing  plants  to  and  from  not  being  much  agitated 

produce  thin,  elongated,  and  flexi-  by  the  wind,  tend  to  produce  long, 

ble  stems.  He  fmther  remarks  that  thin  and  flexible  shoots. 


18  i  HOOK-CLIMBEES.  Chap.  V. 

Eoses,  exhibit  no  spontaneous  revolving  movement. 
If  they  had  possessed  this  power,  and  had  been  capable 
of  twining,  they  would  have  been  jilaced  in  the  class 
of  Twiners  ;  for  some  twiners  are  furnished  with  spines 
or  hooks,  which  aid  them  in  their  ascent.  For  instance, 
the  Hop,  which  is  a  twiner,  has  reflexed  hooks  as  large 
as  those  of  the  Galium  ;  some  other  twiners  have  stiff 
reflexed  hairs ;  and  Diiiladenia  has  a  circle  of  blunt 
spines  at  the  bases  of  its  leaves.  I  have  seen  only 
one  tendril-bearing  plant,  namely,  Smilax  aspera,  which 
is  furnished  with  reflexed  spines ;  but  this  is  the  case 
with  several  branch-climbers  in  South  Brazil  and 
Ceylon ;  and  their  branches  graduate  into  true  tendrils. 
Some  few  plants  aj)parently  depend  solely  on  their 
hooks  for  climbing,  and  yet  do  so  efficiently,  as  certain 
palms  in  the  New  and  Old  Worlds.  Even  some 
climbing  Eoses  will  ascend  the  walls  of  a  tall  house, 
if  covered  with  a  trellis.  How  this  is  effected  I  know 
not;  for  the  young  shoots  of  one  such  Eose,  when 
placed  in  a  pot  in  a  window,  bent  irregularly  towards 
the  light  during  tlie  day  and  from  the  light  during  the 
night,  like  the  shoots  of  any  common  plant ;  so  that 
it  is  not  easy  to  understand  how  they  could  have  got 
under  a  trellis  close  to  the  wall.* 


*  Professor  Asca  Gray  has  ex-  disposed  to  push  into  dark  crevice  s 

plained,  as  it  would  appear,  this  and  away  from  the  light,  so  that 

difficulty  in  his  review  (American  they   would    be   almost   sure   to 

Journal  of  Science,  vol.  xl.  Sept.  place  themselves  under  a  trellis. 

186.5,  p.  282)  of  the  present  work.  He  adds  that  the  lateral  shoots, 

He  has  observed  that  the  strong  made    on   the   following  spring, 

summer  shoots  of  the  Michigan  emerged  from  the  trellis  as  they 

rose  (Jlosa  setigera)  are  strongly  sought  the  light. 


Chap.  V.  EOOT-CLIMBERS.  185 

Boot-cUmhers. — A  good  many  plants  come  under  this 
class,  and  are  excellent  climbers.  One  of  the  most 
remarkable  is  the  Marcgravia  umhellata,  the  stem  of 
which  in  the  tropical  forests  of  South  America,  as  I 
hear  from  Mr,  Spruce,  grows  in  a  curiously  flattened 
manner  against  the  trunks  of  trees ;  here  and  there 
it  puts  forth  claspers  (roots),  which  adhere  to  the 
trunk,  and,  if  the  latter  be  slender,  completely  embrace 
it.  When  tffis  plant  has  climbed  to  the  light,  it  pro- 
duces free  branches  with  rounded  stems,  clad  with  sharp- 
pointed  leaves,  wonderfully  different  in  appearance  from 
those  borne  by  the  stem  as  long  as  it  remains  adherent. 
This  surprising  difference  in  the  leaves,  I  have  also 
observed  in  a  plant  of  Marcgravia  dvhia  in  my  hothouse. 
Koot-climbers,  as  far  as  I  have  seen,  namely,  the  Ivy 
(Hedera  helix),  Ficus  repena,  and  F.  harhatus,  have  no 
power  of  movement,  not  even  from  the  light  to  the  dark. 
As  previously  stated,  the  Hoy  a  carnosa  (Asclepiadaceae) 
is  a  spiral  twiner,  and  likewise  adheres  by  rootlets 
even  to  a  flat  wall.  The  tendril-bearing  Bignonia 
Tweedyana  emits  roots,  which  curve  haK  round  and 
adhere  to  thin  sticks.  The  Tecoma  radicans  (Big- 
noniacese),  which  is  closely  allied  to  many  spontane- 
ously revolving  species,  climbs  by  rootlets;  never- 
theless, its  young  shoots  apparently  move  about  more 
than  can  be  accounted  for  by  the  varying  action  of 
the  light. 

I  have  not  closely  observed  many  root-climbers,  but 
can  give  one  curious  fact.  Ficus  rej^ens  climbs  up 
a  wall  just  like  Ivy ;  and  \Aheu  the  young  rootlets 
9 


18(5  EOOT-CLIMBEES.  Chap.  V. 

are  made  to  press  liglitly  on  slips  of  glass,  they  emit 
after  about  a  week's  interval,  as  I  observed  several 
times,  minute  drops  of  clear  fluid,  not  in  the  least 
milky  like  that  exuded  from  a  wound.  This  fluid 
is  slightly  viscid,  but  cannot  be  drawn  out  into 
threads.  It  has  the  remarkable  property  of  not  soon 
drying  ;  a  drop,  about  the  size  of  half  a  pin's  head,  was 
slightly  spread  out  on  glass,  and  I  scattered  on  it  some 
minute  grains  of  sand.  The  glass  was  left  exposed 
in  a  drawer  during  hot  and  dry  weather,  and  if  the 
fluid  had  been  water,  it  would  certainly  have  dried 
in  a  few  minutes ;  but  it  remained  fluid,  closely 
surrounding  each  grain  of  sand,  during  128  days  :  how 
much  longer  it  would  have  remained  I  cannot  say. 
Some  other  rootlets  were  left  in  contact  with  the  glass 
for  about  ten  days  or  a  fortnight,  and  the  drops  of 
secreted  fluid  were  now  rather  larger,  and  so  viscid 
that  they  could  be  drawn  out  into  threads.  Some 
other  rootlets  were  left  in  contact  during  twenty-three 
days,  and  these  were  firmly  cemented  to  the  glass. 
Hence  we  may  conclude  that  the  rootlets  first  secrete 
a  slightly  viscid  fluid,  subsequently  absorb  the  watery 
parts,  (for  we  have  seen  that  the  fluid  will  not  dry 
by  itself,)  and  ultimately  leave  a  cement.  When  the 
rootlets  were  torn  from  the  glass,  atoms  of  yellowish 
matter  were  left  on  it,  which  were  partly  dissolved 
by  a  drop  of  bisulphide  of  carbon  ;  and  this  extremely 
volatile  fluid  was  rendered  very  much  less  volatile  by 
what  it  had  dissolved. 

As  the  bisulphide   of  carbon   has   a   strong  power 


Chap.  V.  ROOT-CLIMBEES.  187 

of  softening  indurated  caoutcliouc,  I  soaked  in  it 
during  a  short  time  several  rootlets  of  a  plant  which 
had  gTo\^Ti  up  a  plaistered  wall ;  and  I  then  found 
many  extremely  thin  threads  of  transparent,  not  viscid, 
excessively  elastic  matter,  precisely  like  caoutchouc, 
attached  to  two  sets  of  rootlets  on  the  same  branch. 
These  threads  proceeded  from  the  bark  of  the  rootlet 
at  one  end,  and  at  the  other  end  were  jfirmly  attached 
to  particles  of  silex  or  mortar  from  the  wall.  There 
could  be  no  mistake  in  this  observation,  as  I  played 
with  the  threads  for  a  long  time  under  the  microscope, 
drawing  them  out  with  my  dissecting-needles  and 
letting  them  spring  back  again.  Yet  I  looked  re- 
peatedly at  other  rootlets  similarly  treated,  and  could 
never  again  discover  these  elastic  threads.  I  there- 
fore infer  that  the  branch  in  question  must  have  been 
slightly  moved  from  the  wall  at  some  critical  period, 
whilst  the  secretion  was  in  the  act  of  drying,  through 
the  absorption  of  its  watery  parts.  The  genus  Ficus 
abounds  with  caoutchouc,  and  we  may  conclude  from 
the  facts  just  given  that  this  substance,  at  first  in 
solution  and  ultimately  modified  into  an  unelastic 
cement,*  is  used  by  the  Ficus  rejjens  to  cement  its 
rootlets  to  any  surface  which  it  ascends.  Whether 
other  plants,  which  climb  by  their  rootlets,  emit 
any  cement  I  do  not  know;  but  the  rootlets  of  the 

*  Mr.  Spiller  has  recently  shown  a  fine  state  of  division  to  tlie  air, 

(Chemical  Society,  Feb.  16, 1865),  gradually  becomes  converted  into 

iu  a  paper  on   the  oxidation   of  brittle,  resinous  matter,  very  similar 

india-rubber  or  caoutchouc,  that  ^^  ishell-lac. 
tliis  subatance,  when  exposed  in 


188  EOOT-CLIMBERS.  Chap.  V. 

£vy,  placed  against  glass,  barely  adhered  to  it,  yet 
secreted  a  little  yellowish  matter.  I  may  add,  that  the 
rootlets  of  the  Marcgravia  dubia  can  adhere  firmly  to 
smooth  painted  wood. 

Vanilla  aromatica  emits  aerial  roots  a  foot  in  length, 
which  point  straight  down  to  the  ground.  According 
to  Mohl  (p.  49),  these  crawl  into  crevices,  and  when 
they  meet  with  a  thin  support,  wind  round  it,  as  do 
tendrils.  A  plant  which  I  kept  was  young,  and  did 
not  form  long  roots ;  but  on  placing  thin  sticks  in 
contact  with  them,  they  certainly  bent  a  little  to  that 
side,  in  the  course  of  about  a  day,  and  adhered  by 
their  rootlets  to  the  wood ;  but  they  did  not  bend 
quite  round  the  sticks,  and  afterwards  they  re-pursued 
their  downward  course.  It  is  probable  that  these  slight 
movements  of  the  roots  are  due  to  the  quicker  growth 
of  the  side  exposed  to  the  light,  in  comparison  with 
the  other  side,  and  not  because  the  roots  are  sensitive 
to  contact  in  the  same  manner  as  true  tendrils.  Ac- 
cording to  Mohl,  the  rootlets  of  certain  species  of 
Lijcopodium  act  as  tendrils.* 


*  Fritz     Miiller     informs    me  aerial   roots   of   a     Philodendron 

that    he    saw  in    the   forests  of  which  grew  on  the  branches  above. 

South    Brazil     numerous     black  These  roots  therefore  seem  to  be 

strings,  from  some  lines  to  nearly  true  twiners,    though   they    use 

an    inch    in    diameter,    winding  their  powers  to  descend,  instead  of 

spirally  round  the  trunks  of  gi-  to  ascend    like    twining    plants, 

gantic   trees.      At  first  sight  he  The  aerial  roots   of   some  other 

thouglit  that  they  were  the  stems  species    of    Philodendron     hang 

of  twining  plants  which  were  thus  vertically   downwards,   sometimes 

ascending  the  trees;  but  he  after-  for  a  length  of  more  than  fifty  feet, 
wards  found  that  they  were  the 


Chap.  V.  CONCLUDING  EBMARKS.  189 

Concluding  BemarJcs  on  Climhing  Plants. 

Plants  become  climbers,  in  order,  as  it  may  be 
presumed,  to  reacli  the  ligbt,  and  to  expose  a  large 
surface  of  their  leaves  to  its  action  and  to  that  of  the 
free  air.  This  is  effected  by  climbers  with  wonderfully 
little  expenditure  of  organized  matter,  in  comparison 
with  trees,  which  have  to  support  a  load  of  heavy 
branches  by  a  massive  trunk.  Hence,  no  doubt,  it 
arises  that  there  are  so  many  climbing  plants  in  all 
quarters  of  the  world,  belonging  to  so  many  different 
orders.  These  plants  have  been  arranged  under  four 
classes,  disregarding  those -which  merely  scramble  over 
bushes  without  any  special  aid.  Hook-climbers  are 
the  least  efficient  of  all,  at  least  in  our  temperate 
countries,  and  can  climb  only  in  the  midst  of  an 
entangled  mass  of  vegetation.  Root-climbers  are 
excellently  adapted  to  ascend  naked  faces  of  rock 
or  trunks  of  trees ;  when,  however,  they  climb  trunks 
they  are  compelled  to  keep  much  in  the  shade; 
they  cannot  pass  from  branch  to  branch  and  thus  cover 
the  whole  summit  of  a  tree,  for  their  rootlets  require 
long-continued  and  close  contact  with  a  steady  surface 
in  order  to  adhere.  The  two  great  classes  of  twiners 
and  of  plants  with  sensitive  organs,  namely,  leaf- 
climbers  and  tendril-bearers  taken  together,  far  exceed 
in  number  and  in  the  perfection  of  their  mechanism  the 
climbers  of  the  two  first  classes.  Those  which  have 
the  power  of  spontaneously  revolving  and  of  grasping 
objects  with  which  they  come  in  contact,  easily  pass 


190  CONCLUDING   EEMAEKS.  Chap.  V. 

from  branch  to  branch,  and  securely  ramble  over  a 
wide,  sun-lit  surface. 

The  divisions  containing  twining  plants,  leaf-climbers, 
and  tendril-bearers  graduate  to  a  certain  extent  into 
one  another,  and  nearly  all  have  the  same  remarkable 
power  of  spontaneously  revolving.  Does  this  grada- 
tion, it  may  be  asked,  indicate  that  plants  belonging 
to  one  subdivision  have  actually  passed  during  the 
lapse  of  ages,  or  can  pass,  fi'om  one  state  to  the  other  ? 
Has,  for  instance,  any  tendril-bearing  plant  assumed 
its  present  structure  without  having  previously  existed 
as  a  leaf-climber  or  a  twiner?  If  we  consider  leaf- 
climbers  alone,  the  idea  that  they  were  primordially 
twiners  is  forcibly  suggested.  The  internodes  of 
all,  without  exception,  revolve  in  exactly  the  same 
manner  as  twiners  ;  some  few  can  still  twine  well,  and 
many  others  in  an  imperfect  manner.  Several  leaf- 
climbing  genera  are  closely  allied  to  other  genera 
which  are  simple  twiners.  It  should  also  be  observed, 
that  the  possession  of  leaves  with  sensitive  petioles, 
and  with  the  consequent  power  of  clasping  an  object, 
would  be  of  comparatively  little  use  to  a  plant, 
unless  associated  with  revolving  internodes,  by  which 
the  leaves  are  brought  into  contact  with  a  support ; 
although  no  doubt  a  scrambling  plant  would  be  apt, 
as  Professor  Jaeger  has  remarked,  to  rest  on  other  plants 
by  its  leaves.  On  the  other  hand,  revolving  inter- 
nodes, without  any  other  aid,  suffice  to  give  the  power 
of  climbing ;  so  that  it  seems  probable  that  leaf- 
climbers  were  in  most  cases  at  first  twiners,  and  subse- 


Chap.  V.  CONCLUDING   REMARKS.  191 

quently  became  capable  of  grasping  a  support ;  and  this, 
as  we  shall  presently  see,  is  a  great  additional  advantage. 

From  analogous  reasons,  it  is  probable  that  all 
tendril-bearers  were  primordially  twiners,  that  is,  are 
the  descendants  of  plants  having  this  power  and  habit. 
For  the  internodes  of  the  majority  revolve ;  and,  in  a 
few  sjiecies,  the  flexible  stem  still  retains  the  capacity 
of  spirally  twining  round  an  upright  stick.  Tendril- 
bearers  have  undergone  much  more  modification  than 
leaf-climbers ;  hence  it  is  not  surprising  that  their 
supposed  primordial  habits  of  revolving  and  twining 
have  been  more  frequently  lost  or  modified  than  in 
the  case  of  leaf-climbers.  The  three  great  tendril- 
bearing  families  in  which  this  loss  has  occurred  in  the 
most  marked  manner,  are  the  Cucurbitaceae,  Passi- 
floraceae,  and  Yitaceae.  In  the  first,  the  internodes 
revolve ;  but  I  have  heard  of  no  twining  form,  with 
the  exception  (according  to  Palm,  p.  29.  52)  of  Momor- 
dica  halsamina,  and  this  is  only  an  im23erfect  twiner. 
In  the  two  othej*  families  I  can  hear  of  no  twiners ; 
and  the  internodes  rarely  have  the  power  of  revolving, 
this  power  being  confined  to  the  tendrils.  The  inter- 
nodes, however,  of  Passiflora  gracilis  have  the  power 
in  a  perfect  manner,  and  those  of  the  common  Vine  in 
an  imperfect  degree :  so  that  at  least  a  trace  of  the 
supposed  primordial  habit  has  been  retained  by  some 
members  of  all  the  larger  tendril-bearing  groups. 

On  the  view  here  given,  it  may-  be  asked.  Why  have 
the  species  which  were  aboriginally  twiners  been  con- 
verted in  so  many  groups  into  leaf-climbers  or  tendril- 


191  CONCLUDING   REMARKS.  Cuap.  V. 

bearevs  ?  Of  what  advantage  has  this  been  to  them  ? 
Why  did  they  not  remain  simple  twiners  ?  We  can 
see  several  reasons.  It  might  be  an  advantage  to  a 
plant  to  acquire  a  thicker  stem,  with  short  internodes 
bearing  many  or  large  leaves  ;  and  such  stems  are  ill 
fitted  for  tAvining.  Any  one  who  will  look  during 
windy  weather  at  twining  plants  will  see  that  they  are 
easily  blown  from  their  support ;  not  so  with  tendril- 
bearers  or  leaf-climbers,  for  they  quickly  and  firmly 
grasp  their  sujDport  by  a  much  more  efficient  kind  of 
movement.  In  those  plants  which  still  twine,  but  at 
the  same  time  possess  tendrils  or  sensitive  petioles,  as 
some  species  of  Bignonia,  Clematis,  and  Trop£eolum, 
it  can  readily  be  observed  how  incomparably  better 
they  grasp  an  upright  stick  than  do  simple  twiners. 
Tendrils,  from  possessing  this  power  of  grasjiing 
an  object,  can  be  made  long  and  thin ;  so  that 
little  organic  matter  is  expended  in  their  develop- 
ment, and  yet  they  sweep  a  wide  circle  in  search 
of  a  support.  Tendril-bearers  can,  from  their  first 
growth,  ascend  along  the  outer  branches  of  any  neigh- 
bouring bush,  and  they  are  thus  always  fully  exposed 
to  the  light ;  twiners,  on  the  contrary,  are  best  fitted 
to  ascend  bare  stems,  and  generally  have  to  start  in 
the  shade.  Within  tall  and  dense  tropical  forests, 
twining  plants  would  probably  succeed  better  than 
most  kinds  of  tendril-bearers ;  but  the  majority  of 
twiners,  at  least  in  our  temperate  regions,  from  the 
nature  of  their  revolving  movement,  cannot  ascend 
thick  trunks,  whereas  this  can  be  affected  by  tendril- 


CuAP.  V.  CONCLUDING   EEMARKS.  193 

bearers  if  the  trunks  are  branched  or  bear  twigs,  and 
by  some  species  if  the  bark  is  rugged. 

The  advantage  gained  by  climbing  is  to  reach  the 
light  and  free  air  with  as  little  expenditure  of  organic 
matter  as  possible ;  now,  with  twining  plants,  the  stem 
is  much  longer  than  is  absolutely  necessary;  for 
instance.  I  measured  the  stem  of  a  kidney-bean,  which 
had  ascended  exactly  two  feet  in  height,  and  it  was 
three  feet  in  length :  the  stem  of  a  pea,  on  the  other 
hand,  which  had  ascended  to  the  same  height  by  the 
aid  of  its  tendrils,  was  but  little  longer  than  the  height 
reached.  That  this  saving  of  the  stem  is  really  an 
advantage  to  climbing  plants,  I  infer  from  the  species 
that  still  twine  but  are  aided  by  clasping  petioles  or 
tendrils,  generally  making  more  open  spires  than 
those  made  by  simple  twiners.  Moreover,  the  plants 
thus  aided,  after  taking  one  or  two  turns  in  one  direc- 
tion, generally  ascend  for  a  space  straight,  and  then 
reverse  the  direction  of  their  spire.  By  this  means 
they  ascend  to  a  considerably  greater  height,  with  the 
same  length  of  stem,  than  would  otherwise  have  been 
possible ;  and  they  do  this  with  safety,  as  they  secure 
themselves  at  intervals  by  their  clasping  petioles  or 
tendrils. 

We  have  seen  that  tendrils  consist  of  various  organs 
in  a  modified  state,  namely,  leaves,  flower-peduncles, 
branches,  and  perhaps  stipules.  With  respect  to 
leaves,  the  evidence  of  their  modification  is  ample. 
In  young  plants  of  Bignonia  the  lower  leaves  often 
remain  quite  unchanged,  whilst  the  upper  ones  have 


194  CONCLUDING  EEMAEKS.  Chap.  V. 

their  terminal  leaflets  converted  into  perfect  tendrils  ; 
in  Eccremocarjous  I  have  seen  a  single  lateral- branch 
of  a  tendril  replaced  by  a  perfect  leaflet ;  in  Vtcia 
sativa,  on  the  other  hand,  leaflets  are  sometimes 
replaced  by  tendril-branches ;  and  many  other  such 
cases  could  be  given.  But  he  who  believes  in  the 
slow  modification  of  species  will  not  be  content  simply 
to  ascertain  the  homological  nature  of  different  kinds 
of  tendrils ;  he  will  wish  to  learn,  as  far  as  is  possible, 
by  what  actual  steps  leaves,  flower-peduncles,  &c.,  have 
had  their  functions  wholly  changed,  and  have  come  to 
serve  merely  as  prehensile  organs. 

In  the  whole  group  of  leaf-climbers  abundant 
evidence  has  been  given  that  an  organ,  still  subserv- 
ing the  functions  of  a  leaf,  may  become  sensitive  to  a 
touch,  and  thus  grasp  an  adjoining  object.  With 
several  leaf-climbers  the  true  leaves  spontaneously 
revolve ;  and  their  petioles,  after  clasping  a  support 
grow  thicker  and  stronger.  We  thus  see  that  leaves 
may  acquire  all  the  leading  and  characteristic  qualities 
of  tendrils,  namely,  sensitiveness,  spontaneous  move- 
ment, and  subsequently  increased  strength.  If  their 
blades  or  laminae  were  to  abort,  they  would  form  true 
tendrils.  And  of  this  process  of  abortion  we  can  follow 
every  step,  until  no  trace  of  the  original  nature  of 
the  tendril  is  left.  In  Mutisia  clematis,  the  tendril,  in 
shape  and  colour,  closely  resembles  the  petiole  of  one 
of  the  ordinary  leaves,  together  with  the  midribs  of  the 
leaflets,  but  vestiges  of  the  laminae  are  still  occasionally 
retained.     In  four  genera  of  the  Fumariacese  we  can 


Chap.  V.  CONCLUDING   EEMARKS.  liJo 

follow  the  whole  process  of  transformation.  The  termi- 
nal leaflets  of  the  leaf-climbing  F-umaria  officinalis  are 
not  smaller  than  the  other  leaflets ;  those  of  the  leaf- 
climbing  Adlumia  cirrJiosa  are  greatly  reduced ;  those 
of  Corydalis  claviculata  (a  plant  which  may  indifferently 
be  called  a  leaf-climber  or  a  tendril-bearer)  are  either 
reduced  to  microscopical  dimensions  or  have  their 
blades  wholly  aborted,  so  that  this  plant  is  actually  in 
a  state  of  transition ;  and,  finally,  in  the  Dicentra  the 
tendrils  are  perfectly  characterized.  If,  therefore,  we 
could  behold  at  the  same  time  all  the  progenitors  of 
Dicentra,  we  should  almost  certainly  see  a  series  like 
that  now  exhibited  by  the  above-named  three  genera. 
In  Tropseolum  tricolorum  we  have  another  kind  of 
passage ;  for  the  leaves  which  are  first  formed  on  the 
young  stems  are  entirely  destitute  of  laminae,  and 
must  be  called  tendrils,  whilst  the  later  formed  leaves 
have  well-developed  laminae.  In  all  cases  the  acquire- 
ment of  sensitiveness  by  the  mid-ribs  of  the  leaves 
appears  to  stand  in  some  close  relation  with  the  abor- 
tion of  their  laminae  or  blades. 

On  the  view  here  given,  leaf-climbers  were  primor- 
dially  twiners,  and  tendril-bearers  (when  formed  of 
modified  leaves),  were  primordially  leaf-climbers.  The 
latter,  therefore,  are  intermediate  in  nature  between 
twiners  and  tendril-bearers,  and  ought  to  be  related  to 
both.  This  is  the  case :  thus  the  several  leaf-climbing 
species  of  the  Antirrhinese,  of  Solanum,  Cocculus,  and 
Gloriosa,  have  within  the  same  family  and  even  within 
the  same  genus,  relatives  which  are  twiners.     In  the 


196  CO:^CLIJDING  EEMAEKS.  '       Chap.  V. 

genus  Mikania,  there  are  leaf-climbing  and  twining 
species.  The  leaf-climbing  species  of  Clematis  are 
very  closely  allied  to  the  tendril-bearing  Karavelia. 
The  Fumariaceas  include  closely  allied  genera  which  are 
leaf-climbers  and  tendril-bearers.  Lastly,  a  species  of 
Bignonia  is  at  the  same  time  both  a  leaf-climber  and 
a  tendril-bearer;  and  other  closely  allied  species  are 
twiners. 

Tendrils  of  another  kind  consist  of  modified  flower- 
peduncles.  In  this  case  we  likewise  have  many  in- 
teresting transitional  states.  The  common  Yine  •  (not 
to  mention  the  Cardiospermum)  gives  us  every  possible 
gradation  between  a  perfectly  developed  tendril  and  a 
flower-jDcduncle  covered  with  flowers,  yet  furnished  with 
a  branch,  forming  the  flower-tendril,  When  the  latter 
itself  bears  a  few  flowers,  as  we  know  sometimes  is 
the  case,  and  still  retains  the  power  of  clasping  a 
supj)ort,  we  see  an  early  condition  of  all  those  tendrils 
which  have  been  formed  by  the  modification  of  flower- 
peduncles. 

According  to  Mohl  and  others,  some  tendrils  consist 
of  modified  branches :  I  have  not  observed  any  such 
cases,  and  know  nothing  of  their  transitional  states, 
but  these  have  been  fully  described  by  Fritz  Miiller. 
The  genus  Lophospermum  also  shows  us  how  such  a 
transition  is  possible;  for  its  branches  spontaneously 
revolve  and  are  sensitive  to  contact.  Hence,  if  the 
leaves  on  some  of  the  branches  of  the  Lophospermum 
were  to  abort,  these  branches  would  be  converted 
into  true  tendrils.     Nor  is  there  anything  improbable 


Chap.  V.  CONCLUDING   REMARKS.  1 97 

in  certain  branches  alone  being  thus  modified,  whilst 
others  remained  unaltered;  for  we  have  seen  with  cer- 
tain varieties  of  Phaseolus,  that  some  of  the  branches 
are  thin,  flexible,  and  twine,  whilst  other  branches 
on  the  same  plant  are  stiff  and  have  no  such  power. 

If  we  inquire  how  a  petiole,  a  branch  or  flower- 
peduncle  first  became  sensitive  to  a  touch,  and 
acquired  the  power  of  bending  towards  the  touched 
side,  we  get  no  certain  answer.  Nevertheless  an  ob- 
servation by  Hofmeister*  well  deserves  attention, 
namely,  that  the  shoots  and  leaves  of  all  plants,  whilst 
young,  move  after  being  shaken.  Kerner  also  finds,  as 
we  have  seen,  that  the  flower-peduncles  of  a  large 
number  of  plants,  if  shaken  or  gently  rubbed  bend  to 
this  side.  And  it  is  young  petioles  and  tendrils, 
whatever  their  homological  nature  may  be,  which 
move  on  being  touched.  It  thus  appears  that  climbing 
plants  have  utilized  and  perfected  a  widely  distributed 
and  incipient  capacity,  which  capacity,  as  far  as  we 
can  see,  is  of  no  service  to  ordinary  plants.  If  we 
further  inquire  how  the  stems,  petioles,  tendrils,  and 
flower-peduncles  of  climbing  plants  first  acquired 
their  power  of  spontaneously  revolving,  or,  to  speak 
more  accurately,  of  successively  bending  to  all  points 
of  the  compass,  we  are  again  silenced,  or  at  most  can 
only  remark  that  the  power  of  moving,  both  spon- 
taneously and   from  various   stimulants,  is   far   more 


*  Quoted    by    Cohn,    iu    his       handl.   der  Schlesischen  Gesell. 
remarkable  memoir,  "  Contractile       1861,  Heft  i.  s.  35. 
Gewebe  im  Pflanzenreiche,"  '  Ab- 


198  CONCLUDING  REMARKS.  Chap.  V. 

common  with  plants,  than  is  generally  sujjposed  to  be 
the  case  by  those  who  have  not  attended  to  the  subject. 
I  have  given  one  remarkable  instance,  namely  that  of 
the Maurandia  semjperJlorens,ihe  young  flower-peduncles 
of  which  spontaneously  revolve  in  very  small  circles, 
and  bend  when  gently  rubbed  to  the  touched  side ; 
yet  this  plant  certainly  does  not  profit  by  these  two 
feebly  develojDcd  powers.  A  rigorous  examination  of 
other  young  plants  would  probably  show  slight  spon- 
taneous movements  in  their  stems,  petioles  or  pe- 
duncles, as  well  as  sensitiveness  to  a  touch.*  We  see 
at  least  that  the  Maurandia  might,  by  a  little  aug- 
mentation of  the  powers  which  it  already  possesses, 
come  first  to  grasp  a  support  by  its  flower-peduncles, 
and  then,  by  the  abortion  of  some  of  its  flowers  (as  with 
Vitis  or  Cardiosi^ermum),  acquire  perfect  tendrils. 

There  is  one  other  interesting  point  which  deserves 
notice.  We  have  seen  that  some  tendrils  owe  their 
origin  to  modified  leaves,  and  others  to  modified  flower- 
peduncles  ;  so  that  some  are  foliar  and  others  axial 
in  their  nature.  It  might  therefore  have  been  expected 
that  they  would  have  presented  some  difference  in 
fimction.     This  is  not  the  case.     On  the  contrary,  they 


*  Such  slight  spontaneoua  Bhown  in  relation  to  our  present  sub- 
movements,  I  now  find,  have  been  ject  ('  Jenaischen  Zeitschrift,'  Bd. 
for  some  time  known  to  occur,  V.  Heft  2,  p.  133)  that  the  stems, 
for  instance  with  the  flower-stems  whilst  young,  of  an  Alisma  find 
of  Brassica  napus  and  with  the  of  a  Linum  are  continually 
leaves  of  many  plants  :  Sachs'  performing  slight  movements  to 
'Text- Book  of  Botany'  1875,  pp.  all  points  of  the  compass,  like 
7G6,  785.     Fritz  Miiller  also  has  those  of  climbing  plants. 


Chap.  V.  CONCLUDING   REiAIAEKS.        '  199 

present  the  most  complete  identity  in  their  several 
characteristic  powers.  Tendrils  of  both  kinds  sponta- 
neously revolve  at  about  the  same  rate.  Both,  when 
touched,  bend  quickly  to  the  touched  side,  and  after- 
wards recover  themselves  and  are  able  to  act  affaiu. 
In  both  the  sensitiveness  is  either  confined  to  one  side 
or  extends  all  round  the  tendril.  Both  are  either 
attracted  or  repelled  by  the  light.  The  latter  property 
is  seen  in  the  foliar  tendrils  of  Bignonia  cap-eolata 
and  in  the  axial  tendrils  of  Amjjehj^sis.  The  tips 
of  the  tendrils  in  these  two  plants  become,  after  con- 
tact, enlarged  into  discs,  which  are  at  first  adhesive 
by  the  secretion  of  some  cement.  Tendrils  of  both 
kinds,  soon  after  grasping  a  suj)port,  contract  spirally ; 
they  then  increase  greatly  in  thickness  and  strength. 
When  we  add  to  these  several  points  of  identity  the 
fact  that  the  petiole  of  Solanum  jasminoides,  after 
it  has  clasped  a  support,  assumes  one  of  the  most 
characteristic  features  of  the  axis,  namely,  a  closed  ring 
of  woody  vessels,  we  can  hardly  avoid  asking,  whether 
the  difference  between  foliar  and  axial  organs  can  be 
of  so  fundamental  a  nature  as  is  generally  supposed  ?  * 
We  have  attempted  to  trace  some  of  the  stages  in 
the  genesis  of  climbing  plants.  But,  diu'ing  the 
endless  fluctuations  of  the  conditions  of  life  to  which 
all  organic  beings  have  been  exposed,  it  might  be 
expected  that  some  climbing  plants  would  have  lost 


*  Mr.  Herbert  Spencer  has  much  force  that  there  is  no  fun- 
recently  argued  ('  Principles  of  damental  distinction  between  the 
Biology,'  1865,  p.  37  et  seq.)  with       foliar  and  axial  organs  of  plants. 


200  CONCLUDING   REMARKS.  Chap.  V. 

the  habit  of  climbing.  lu  the  cases  given  of  certain 
South  African  plants  belonging  to  great  twining  fami- 
lies, which  in  their  native  country  never  twine,  but 
reassume  this  habit  when  cultivated  in  England,  we 
have  a  case  in  point.  In  the  leaf-climbing  Clematis 
flammula,  and  in  the  tendril-bearing  Vine,  we  see  no 
loss  in  the  power  of  climbing,  but  only  a  remnant  of  the 
revolving  power  which  is  indispensable  to  all  twiners, 
and  is  so  common  as  well  as  so  advantageous  to  most 
climbers.  In  Tecoma  raclicans,  one  of  the  Bignoniacese, 
we  see  a  last  and  doubtful  trace  of  the  power  of 
revolving. 

With  respect  to  the  abortion  of  tendrils,  certain 
cultivated  varieties  of  Cucurbita  jpepo  have,  according 
to  Naudin,*  either  quite  lost  these  organs  or  bear 
semi-monstrous  representatives  of  them.  In  my 
limited  experience,  I  have  met  with  only  one  ap- 
parent instance  of  their  natural  suppression,  namely, 
in  the  common  bean.  All  the  other  species  of  Vicia, 
I  believe,  bear  tendrils ;  but  the  bean  is  stiff  enough 
to  support  its  own  stem,  and  in  this  species,  at  the 
end  of  the  petiole,  where,  according  to  analogy,  a  ten- 
dril ought  to  have  existed,  a  small  pointed  filament 
projects,  about  a  third  of  an  inch  in  length,  and  which 
is  probably  the  rudiment  of  a  tendril.  This  may  be 
the  more  safely  inferred,  as  in  young  and  unhealthy 
specimens  of  other  tendril-bearing  plants  similar  rudi- 
ments may  occasionally  be   observed.      In  the  bean 


*  Annales  des  Sc  Nat.  4th  series,  Bot.  torn.  vi.  1 856,  p.  31. 


CfJAi'.  Y.  CONCLUDING   REMARKS.  201 

these  filaments  are  variable  in  shape,  as  is  so  fre- 
quently the  case  with  rudimentary  organs ;  they  are 
either  cylindrical,  or  foliaceous,  or  are  deeply  furrowed 
on  the  upper  surface.  They  have  not  retained  any 
vestige  of  the  power  of  revolving.  It  is  a  curious 
fact,  that  many  of  these  filaments,  when  foliaceous, 
have  on  their  lower  surfaces,  dark-coloured  glands  like 
those  on  the  stipules,  which  excrete  a  sweet  fluid ;  so 
that  these  rudiments  have  been  feebly  utilized. 

One  other  analogous  case,  though  hypothetical,  is 
worth  giving.  Nearly  all  the  species  of  Lathyrus 
possesses  tendrils ;  but  L.  nissolia  is  destitute  of  them. 
This  plant  has  leaves,  which  must  have  struck  every 
one  with  surprise  who  has  noticed  them,  for  they  are 
quite  unlike  those  of  all  coramon  papilionaceous 
plants,  and  resemble  those  of  a  grass.  In  another 
species,  L.  aphaca,  the  tendril,  which  is  not  highly 
developed  (for  it  is  unbranched,  and  has  no  spon- 
taneous revolving-power),  replaces  the  leaves,  the 
latter  being  replaced  in  function  by  large  stipules. 
Now  if  we  suppose  the  tendrils  of  L.  aphaca  to  become 
flattened  and  foliaceous,  like  the  little  rudimentary 
tendrils  of  the  bean,  and  the  large  stipules  to  become 
at  the  same  time  reduced  in  size,  from  not  being  any 
longer  wanted,  we  should  have  the  exact  counterj)art 
of  L.  nissolia,  and  its  curious  leaves  are  at  once 
rendered  intelligible  to  us. 

It  may  be  added,  as  serving  to  simi  up  the  foregoing 
views  on  the  origin  of  tendril-bearing  plants,  that  L. 
nissolia  is  probably  descended  from  a  plant  which  was 


202  CONCLUDING   REMAEKS.  Chap,  V. 

primordially  a  twiner  ;  this  then  became  a  leaf-climber, 
the  leaves  being  afterwards  converted  by  degrees  into 
tendrils,  with  the  stipules  greatly  increased  in  size 
through  the  law  of  compensation.*  After  a  time  the 
tendrils  lost  their  branches  and  became  simple ;  they 
then  lost  their  revolving-power  (in  which  state  they 
would  have  resembled  the  tendrils  of  the  existing 
L.  apliaca),  and  afterwards  losing  their  prehensile 
power  and  becoming  foliaceous  would  no  longer  be 
thus  designated.  In  this  last  stage  (that  of  the  exist- 
ing L.  nissoUa)  the  former  tendrils  would  reassume 
their  original  function  of  leaves,  and  the  stipules  which 
were  recently  much  developed  being  no  longer  wanted, 
would  decrease  in  size.  If  species  become  modified  in 
the  course  of  ages,  as  almost  all  naturalists  now  admit, 
we  may  conclude  that  L.  nissolia  has  passed  through  a 
series  of  changes,  in  some  degree  like  those  here 
indicated. 

The  most  interesting  point  in  the  natural  history  of 
climbing  plants  is  the  various  kinds  of  movement 
which  they  display  in  manifest  relation  to  their  wants. 
The  most  different  organs — stems,  branches,  flower- 
peduncles,  petioles,  mid-ribs  of  the  leaf  and  leaflets, 
and  apparently  aerial  roots — all  possess  this  power. 

The  first  action  of  a  tendril  is  to  place  itself  in  a 
proper  position.     For  instance,  the  tendril  of  Cobaja 


"  Moqnin-Tandon  (!filements  de  this  nature  was  suddenly  effected ; 

Te'ratologie,  1841,  p.   156)  gives  for   the    leaves    completely   dis- 

the  case  of   a  monstrous  bean,  in  appeared  and  the  stipules  grew  to 

wldch  a  case  of  compensation  of  an  enormous  size. 


CuAP.  V.  CONCLUDING   REMARKS.  203 

first  rises  vertically  up,  with  its  branches  divergent 
and  with  the  terminal  hooks  turned  outwards ;  the 
young  shoot  at  the  extremity  of  the  stem  is  at  the 
same  time  bent  to  one  side,  so  as  to  be  out  of  the  way. 
The  young  leaves  of  Clematis,  on  the  other  hand, 
prepare  for  action  by  temporarily  curving  themselves 
downwards,  so  as  to  serve  as  grapnels. 

Secondly,  if  a  twining  plant  or  a  tendril  gets  by 
any  accident  into  an  inclined  position,  it  soon  bends 
upwards,  though  secluded  from  the  light.  The  guid- 
ing stimulus  no  doubt  is  the  attraction  of  gravity,  as 
Andrew  Knight  showed  to  be  the  case  with  germinat- 
ing plants.  If  a  shoot  of  any  ordinary  plant  be  placed 
in  an  inclined  position  in  a  glass  of  water  in.  the  dark, 
the  extremity  will,  in  a  few  hours,  bend  upwards ;  and 
if  the  position  of  the  shoot  be  then  reversed,  the 
downward-bent  shoot  reverses  its  curvature;  but  if 
the  stolon  of  a  strawberry,  which  has  no  tendency  to 
grow  upwards,  be  thus  treated,  it  will  curve  do^vnwards 
in  the  direction,  of,  instead  of  in  opposition  to,  the 
force  of  gravity.  As  with  the  strawberry,  so  it  is 
generally  with  the  twining  shoots  of  the  Hibbertia 
dentata,  which  climbs  laterally  from  bush  to  bush ;  for 
these  shoots,  if  placed  in  a  position  inclined  downwards, 
show  little  and  sometimes  no  tendency  to  curve  up- 
wards. 

Thirdly,  climbing  plants,  like  other  plants,  bend 
towards  the  light  by  a  movement  closely  analogous  to 
the  incurvation  which  causes  them  to  revolve,  so  that 
their  revolving  movement  is  often  accelerated  or  retarded 


204.  CONCLUDING   REMARKS.  Chap.  V. 

in  travelling  to  or  from  the  light.  On  the  other 
hand,  in  a  few  instances  tendrils  bend  towards  tlie 
dark. 

Fourthly,  we  have  the  spontaneous  revolving  move- 
ment which  is  independent  of  any  outward  stimulus, 
but  is  contingent  on  the  youth  of  the  part,  and  on 
vigorous  health ;  and  this  again  of  course  depends  on 
a  proper  temperature  and  other  favourable  conditions 
of  life. 

Fifthly,  tendrils,  whatever  their  homological  nature 
may  be,  and  the  petioles  or  tips  of  the  leaves  of  leaf- 
climbers,  and  apparently  certain  roots,  all  have  the 
power  of  movement  when  touched,  and  bend  quickly 
towards  the  touched  side.  Extremely  slight  pressure 
often  suffices.  If  the  pressure  be  not  permanent,  the 
part  in  question  straightens  itself  and  is  again  ready 
to  bend  on  being  touched. 

Sixthly,  and  lastly,  tendrils,  soon  after  clasping  a 
support,  but  not  after  a  mere  temporary  curvature, 
contract  spirally.  If  they  have  not  come  into  contact 
with  any  object,  they  ultimately  contract  spirally,  after 
ceasing  to  revolve ;  but  in  this  case  the  movement  is 
useless,  and  occurs  only  after  a  considerable  lapse  of 
time. 

With  respect  to  the  means  by  which  these  various 
movements  are  effected,  there  can  be  little  doubt  from 
the  researches  of  Sachs  and  H.  de  Vries,  that  they  are 
due  to  unequal  growth  ;  but  from  the  reasons  already 
assigned,  I  cannot  believe  that  this  explanation  applies 
to  the  rapid  movements  from  a  delicate  touch. 


CliAP.  V.  CONCLUDING    REMAEKS.  205 

Finally,  climbing  plants  are  sufficiently  nnmerous  to 
form  a  conspicuous  feature  in  the  vegetable  kingdom, 
more  especially  in  tropical  forests,  America,  which  so 
abounds  with  arboreal  animals,  as  Mr.  Bates  remarks, 
likewise  abounds  according  to  Mohl  and  Palm  with 
climbing  plants ;  and  of  the  tendril-bearing  plants 
examined  by  me,  the  highest  developed  kinds  are 
natives  of  this  grand  continent,  namely,  the  several 
species  of  Bignonia,  Eccremoear^us,  Cdbsea,  and  Ampe- 
lopsis.  But  even  in  the  thickets  of  our  temperate 
regions  the  number  of  climbing  species  and  individuals 
is  considerable,  as  will  be  found  by  counting  them. 
They  belong  to  many  and  widely  different  orders.  To 
gain  some  rude  idea  of  their  distribution  in  the  vegetable 
series,  I  marked,  from  the  lists  given  by  Mohl  and  Palm 
(adding  a  few  myself,  and  a  competent  botanist,  no 
doubt,  could  have  added  many  more),  all  those  families 
in  Lindley's  '  Vegetable  Kingdom '  which  include 
twiners,  leaf-climbers,  or  tendril-bearers.  Lindley 
divides  Phanerogamic  plants  into  fifty -nine  Alliances  ; 
of  these,  no  less  than  thirty-five  include  climbing  plants 
of  the  above  kinds,  hook  and  root-climbers  being  ex- 
cluded. To  these  a  few  Cryptogamic  plants  must  be 
added.  When  we  reflect  on  the  wide  separation  of  these 
plants  in  the  series,  and  when  we  know  that  in  some  of 
the  largest,  well-defined  orders,  such  as  the  Compositse, 
Hubiaceoe,  Scrophulariacese,  Liliaceae,  &c.,  species  in 
only  two  or  three  genera  have  the  power  of  climbing, 
the  conclusion  is  forced  on  our  minds  that  the  capacity  of 
revolving,  on  which  most  climbers  depend;  is  inherent, 


206  CONCLUDING   EEMAEKS.  Chap.  V. 

though   undeveloped,  in   almost   every   plant   in   the 
vegetable  kingdom. 

It  has  often  been  vaguely  asserted  that  plants  are 
distinguished  from  animals  by  not  having  the  power 
of  movement.  It  should  rather  be  said  that  j)lants 
acquire  and  display  this  power  only  when  it  is  of  some 
advantage  to  them ;  this  being  of  comjjaratively  rare 
occurrence,  as  they  are  affixed  to  the  ground,  and  food 
is  brought  to  them  by  the  air  and  rain.  We  see 
how  high  in  the  scale  of  organization  a  plant  may 
rise,  when  we  look  at  one  of  the  more  perfect  tendril- 
bearers.  It  first  places  its  tendrils  ready  for  action, 
as  a  polypus  places  its  tentacula.  If  the  tendril  be 
displaced,  it  is  acted  on  by  the  force  of  gravity  and 
rights  itself.  It  is  acted  on  by  the  light,  and  bends 
towards  or  from  it,  or  disregards  it,  whichever  may  be 
most  advantageous.  During  several  days  the  tendrils 
or  internodes,  or  both,  spontaneously  revolve  with  a 
steady  motion.  The  tendril  strikes  some  object,  and 
quickly  curls  round  and  firmly  grasps  it.  In  the 
course  of  soine  hours  it  contracts  into  a  spire,  dragging 
up  the  stem,  and  forming  an  excellent  spring.  All 
movements  now  cease.  By  growth  the  tissues  soon 
become  wonderfully  strong  and  durable.  The  tendril 
has  done  its  work,  and  has  done  it  in  an  admirable 
manner. 


INDEX. 


Abortion  of  tendrils,  200 

Adluniia  cirrhosa,  76 

Advantages  gained  by  climbing,  189 

Alisma,  spontaneous  movement  of,  198 

Anguria  Warscewiczii,  136  [205 

Amei-ica,  number  of  climbing  plants  of, 

Ampelopsis  hederacea,  144 

Bates,  Mr.,  on  number  of  arboreal 
animals  in  America,  205  [202 

Bean,  common,  abortion  of  tendrils,  200, 

Bignonia,  A-arious  species  of,  bearing 
tendrils,  86 

Brassica  napus,  spontaneous  movement 
of  peduncles,  198 

Bryonia  dioica,  131,  136 

Caoutchouc  secreted  by  roots  of  Ficus 
repens,  186 

Cardiospermum  halicacabum,  150 
■  Ceropegia  Gardne'rii,  6 

,  manner  of  twining,  20 

,    a    species    which    has    lost    the 

power  of  twining  in  South  Africa,  42 

Cissus  discolor,  143 

Clematis,  various  species  of,  leaf- 
climbers,  46 

Coba?a  scandens,  106 

Combretum,  41 

Corydalis  claviculata,  121 

Cucurbitacese,  nature  of  tendrils,  127 

Cucurbita  pepo,  aborted  tendrils,  200 

Cuscuta,  stems  of,  irritable,  17,  71 

Dicentra  thalictrifolia,  124 

Dipladenia,  furnished  with  hooks,  184 

Discs,  adhesive,  developed  by  tendrils, 
94,  100,  135,  136,  145,  179 

Dutrochet,  reference  to  papers  on 
climbing  plants,  1 

Eccremocarpus  scaber,  103 

Echinocystis  lobata,  128 

Ferns,  twining,  38 

Ficus  repens,  a  root-climber,  185 

Flagellaria  Indica,  79 

Flower-peduncles  of  Maurandia  sensi- 
tive, and  revolve  spontaneously,  67 

Fumaria  officinalis,  75 

Galium  aparine,  a  hook-climber,  183 

Gradations  of  structure  leading  to  the 
development  of  perfect  tendrils,  195, 
196 


Gray,    Asa,    reference    to     paper     on 

tendrils  of  Cucurbitacea;,  1 
on  tendrils  of  Passiflora,  1 54 

on  Rosa  setigera,  1 84 

Gloriosa  Plantii,  78 

Hanburya  Mexicana,  134 

Harvey,  Prof.,  on  the  loss  of  power  of 
twining,  42 

Hedei.i  helix,  185,  188 

Hibbertia  dentata,  35  [203 

,  shoots  of,  turn  downwards, 

Hofraeister,    on    irritability    of  young 
petioles,  197 

Hook-climbers,  183 

Hop,  powers  of  twining,  2 

Hoya  carnosa,  6,  43,  185 

Humulus  lupulus,  2 

India-rubber  secreted  by  roots  of  Ficus 
repens,  186 

Ipomoea  argyraeoides,  42 

Ivy,  185,  188  [183,  199 

Jaeger,  Prof.  G.,   on   climbing  plants, 

Kerner,  on  the  irritability  of  Hower- 
peduncles,  197 

Lathy rus  aphaca,  115 

,    probable   manner    of    de- 
velopment of  its  tendrils,  201 

,  grandiflorus,  116 

nissolia,  grass-like  leaves  replacing 

tendrils,  201 

Leaves,  position  of,  on  twining  plants,  19 

Leaf-climbers,  45 
■         summary  on,  81 

climb   more   securely  than 

twiners,  192 

Leon,  M.,  on  a  variety  of  Phaseolus,  42 

,  on  spiral  contraction  of  ten- 
drils, 166 

Light,  action  on  twining  plants,  40 

,  avoidance  of,  by  tendrils,  98,  105, 

110,  138,  145,  175 

Linum,  spontaneous  movement  of,  198 

Loasa  aurantiaca,  34 

Lophospermum  scandens,  71 

Lygodium  articulatum,  38 

M'Nab,  Dr.,  on  Ampelopsis  Veitchii,  146 

Marcgravia,  a  root-climber,  185,  188 

Masters,  Di-.  M.,  on  torsion,  10 


208 


INDEX. 


JIasters,  Dr.  M.,  on  the  woody  vessels  of 

petioles,  75 
Maurandia,  a  leaf-climbir,  66 
Mikania  scandens,  33 
Wohl,  Hugo,  reference  to  work  of,  ] 
Moquin-Tandon,  on  the  ab(  rtion  of  the 

leaves  of  the  bean,  202 
■  Miiller,  Fritz,  on  the  structure  of  the 

wood  of  climbing  plants,  44 
on  plants  scrambling  over 

other  plants,  183 

on  the    development    of 


branches  into  tendrils,  84 

•  on  roots  of  Philodendron, 


188 

on  the  spontaneous  move- 
ments of  certain  plants,  198 

Mutisia  clematis,  116 

Naudin  on  abortion  of  tendrils,  200 

Nepenthes,  80 

Nutation,  revolving,  11 

Ophioglossum  Japonicum,  77 

Palm,  reference  to  work  of,  1 

Passiflora  acerifolia,  154 

gracilis,  153 

punctata,  156 

quadrangularis,  157 

Paulliuia,  153 

Pea,  common,  112 

Peduncles  of  Maurandia  sensitive  and 
revolve  spontaneously,  67 

Phaseolus,  torsion  of  axes,  9 

,  non-twining  variety,  42 

Philodendron,  roots  of,  188 

Pisum  sativum,  112 

Polygonum  convolvulus,  41 

Rhodochiton  volubile,  70 

Roots  acting  like  tendrils,  188 

Root-climbers,  185 

Rosa  setigera,  shoots  bend  from  the 
light,  184 

Rubus  australis,  183 

Sachs,  Prof.,  on  torsion,  9 

on  cause  of  revolving  move- 
ment, 22 

on  tendrils  adapted  to  clasp 

supports  of  different  thickness,  1,76 

on  cause  of  movement  of  ten- 
drils when  touched,  180 

Sensitiveness  of  tendrils,  nature  of.  197 


Serjania,  152 

Smilax  aspera,  118,  184 

Spencer,  Herbert,  on  the  relation  of  axial 

and  foliar  orga'ns,  199 
Spiller,  Mr.,  on  the  oxidation  of  india- 
rubber,  187 
Spruce,  Mr.,  on  Marcgravia,  185 
Solanum  dulcamara,  34,  43 

jasminoides,  72 

Spiral  contraction  of  tendrils,  158 
Summary  on  twining  plants,  39 
Summary  on  leaf-climbers,  81 
Summary  on  the  movements  of  tendrils, 
169,  202  [13 

Summit  of  twining  plants,  often  hooked, 
Support,    thickness     of,    round    which 

plants  can  twine,  22,  36 
,  thickness  of,  which  can    be  em- 
braced by  tendrils,  176 
Tacsonia  manicata,  158 
Tamus  elephantipes,  41 
Tecoma  radicans,  43,  185 
Tendrils,  history  of  our  knowledge  of,  85 

,  spiral  contraction  of,  158 

,  summary  on,  169,  202  [180 

,  cause  of  movement  when  touched, 

Tendril-bearers    climb    more    securely 

than  twiners,  192 
Tendrils,  abortion  of,  200 
Torsion  of  the  axes  of  twining  plants,  7 
Tropajolum,    various   species    of,    leaf- 
climbers,  60 
Twining  plants,  2 

,  shoots  of,  sometimes  sponta- 


neously become  spiral,  17 
table    of  rates  of  revolution 


of  various  species,  24 

anomalous  cases  of,  41 


Twisting  of  the  axes  of  twining  plants,  7 
Vanilla  aromatica,  188 
Vine,  common,  137 
Virginian  creeper,  144 
Vries,  H.  de,  on  torsion,  9 

on  cause  of  revolving  movement,  22 

on  spiral  contraction  of  ten- 


drils, 160,  165 
cause  of  mc 


.  ements  of  ten- 


drils, 180 
Vitis  vinifera,  137 
Zahonia  Indica,  136 


Works  of  Charles  Darwin. 


JOURNAL  OF  RESEARCHES  into  the  Natural  History  and  Ge- 
ology of  the  Countries  visited  during  the  Voyage  of  H.  M.  S.  Beagle  round  the 
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work  has  been  for  some  time  before  the  public,  and  has  won  a  high  place  among 
readers  of  every  class.  It  is  not  so  scientific  as  to  be  above  the  comprehension  of  in- 
telligent readers  who  are  not  scientific.  Some  facts  and  species,  new  even  to  the  sci- 
entific, are  brought  to  light.  Darwin's  transparent,  eloquent  style  richly  illuminates 
his  observations.  The  weightier  matters  to  which  he  alludes  are  interspersed  among 
more  familiar  observations,  such  as  would  naturally  be  made  by  a  traveler  passing 
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THE  ORIGIN  OF  SPECIES  by  Means  of  Natural  Selection,  or 
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ence, and  having  spent  many  years  in  gathering  and  sifting  materials  for  his  present 
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"  In  this  work  Mr.  Darwin's  patient  and  painstaking  methods  of  investigation  ap- 
pear to  the  best  possible  advantage.  It  is  impossible  to  read  it  without  enthusiastic 
admiration  for  the  ingenuity  which  he  displays  in  devising  tests  to  determine  the  char- 
acteristics of  the  plants,  the  peculiarities  of  which  he  is  studying,  and,  as  is  always 
the  case  with  him,  he  presents  the  conclusions  arrived  at  in  language  so  lucid  that  he 
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"  Mr.  Darwin's  book  may  be  held  up  as  a  model  of  what  a  treatise  should  be  that 
is  addressed  to  intelligent  readers,  a  majority  of  whom,  it  is  to  be  presumed,  have  no 
special  acquaintance  with  the  matter  under  consideration.  In  style  it  is  strongly 
marked  with  Darwinian  characteristics.  The  opening  passage,  indeed,  allowing  for 
difference  of  subject,  is  drawn  up  almost  precisely  in  the  same  way  as  that  which  ushers 
in  Chapter  I.  of  the  'Origin  of  Species.'  We  have  laid  before  us  the  circumstances 
that  led  the  author  to  pursue  his  researches  in  the  first  instance,  so  far  back  as  i860; 
then,  step  by  step,  we  are  treated  to  the  history  of  those  researches ;  fact  is  added  to 
fact,  inference  to  inference,  till  at  length  the  body  of  evidence,  direct  and  indirect,  be- 
comes so  overwhelming,  that  there  is  as  little  chance  of  controverting  Mr.  Darwin's 
conclusions  as  there  is  for  a  fly  to  escape  when  once  it  has  been  caught  in  the  cruel 
embrace  of  a  sun-dew.  The  modesty,  the  perfect  candor,  the  scrupulous  care  to  ac- 
knowledge the  labors  of  others,  even  in  the  most  trifling  particulars,  are  as  apparent  in 
this  as  in  the  rest  of  Mr.  Darwin's  books.  These  Darwinian  characteristics,  as  we 
venture  to  call  them,  are  only  equaled  by  the  apparently  ine.\haustible  patience  with 
which  he  has  pursued  his  observations  and  experiments  throughout  many  years." — 
London  A  thenceuvi. 

"  In  this  work  Mr.  Darwin's  patient  and  painstaking  methods  of  investigation  ap- 
pear to  the  best  possible  advantage.  It  is  impossible  to  read  it  without  enthusiastic 
admiration  for  the  ingenuity  which  he  displays  in  devising  tests  to  determine  the  char- 
acteristics of  the  plants,  the  peculiarities  of  which  he  is  studying,  and,  as  is  always  the 
case  with  him,  he  presents  the  conclusions  arrived  at  in  language  so  lucid  that  he  who 
reads  simply  for  information  is  sure  to  be  attracted  and  charmed  quite  as  much  as  the 
professional  student." — N.  V.  Times. 

"  As  a  model  of  scientific  inquiry,  his  work  will  scarcely  find  a  parallel  in  any  lan- 
guage. It  is  utterly  free  from  the  diffuse  verbiage  which  corrupts  the  style  of  so  many 
of  the  prominent  German  naturalists,  and  from  the  subtile  refinements  which  so  often 
throw  an  air  of  romance  around  the  physical  speculations  of  French  writers.  In  Eng- 
lish scientific  literature  it  has  no  superior  in  acuteness  of  thought,  candor  of  judgment, 
and  felicity  of  expression. 

"  Mr.  Darwin's  manner  is  equally  remote  from  the  vehemence  ot  the  polemic  aiid  the 
indifference  of  the  cold-blooded  observer.  His  pages  are  warm  with  deep  human  inter- 
est, but  an  interest  inspired  by  the  love  of  truth  and  knowledge,  not  by  personal  passion. 
His  anxious  endeavor  for  accurate  observation  is  evinced  in  every  line  of  his  writings, 
and,  if  he  clings  to  theories  with  the  earnestness  of  a  discoverer,  he  clings  still  more  de- 
votedly to  the  facts  of  Nature  which  he  undertakes  to  interpret.  The  scope  of  his  ex- 
periments illustrates  the  rare  fertility  of  his  mind,  as  well  as  his  wonderful  patience. 
The  thoroughness  of  their  execution  is  fully  equal  to  the  ingenuity  of  th^ir  conception. 
No  detail  appears  to  escape  his  notice,  no  inadvertence  mars  the  harmony  of  his  state- 
ment, no  unwise  haste  disturbs  the  clearness  and  serenity  of  his  judgment,  and  even  if 
one  could  be  indifferent  to  his  volume  as  a  scientific  production,  it  must  still  be  admired 
as  a  masterpiece  of  intellectual  workmanship." — N.  V.  Tribune. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  V. 


NEW  WORK    BY  MR.  DARWIN. 


Now  ready.     I  vol.     Thick  i2mo.     With  Illustrations.     $3.50. 

The  Expression  of  the  Emotions 
in  Man  and  Animals. 

By  CHARLES  DARWIN,  F.  R.  S.,  Author  of  the  "  Origin  of  Species,"  etc.,  etc. 

"  Whatever  one  thinks  of  Mr.  Darwin's  theory,  it  must  be  admitted  that  his  great 
powers  of  observation  are  as  conspicuous  as  ever  in  this  inquiry.  During  a  space  ot 
more  than  thirty  years,  he  has,  with  exemplary  patience,  been  accumulating  inforraa- 
tion  from  all  available  sources.  The  result  of  all  this  is  undoubtedly  the  collection  of  a 
mass  of  minute  and  trustworthy  information  which  must  possess  the  highest  value, 
whatever  may  be  the  conclusions  ultimately  deduced  from  it." — London  Times. 

"  It  is  almost  needless  to  say  that  Mr.  Darwin  has  brought  to  this  work  vast  stores 
of  erudition,  accumulated  treasures  of  careful  observation,  and  all  the  devices  of  an 
acute  and  fertile  ingenuity ;  for  these  are  qualities  which  are  conspicuous  in  all  he 
writes.  But  it  may  be  as  well  to  add  that  the  book  is  very  attractive  even  to  general 
readers.  It  is  comparatively  light  and  easy  reading,  full  of  amusing  anecdote  ;  and  the 
illustrations,  whether  due  to  the  sun's  rays  or  to  the  engraver's  point,  are  excellent." — 
Guardmfi. 

"  Those  of  our  readers  who  know  the  charm  of  Darwin's  former  works,  how  he 
leads  his  readers  on  to  his  conclusions  in  the  clearest  and  most  attractive  English,  will 
experience  more  than  their  usual  treat  when  they  sit  down  to  this  book.  Never  was 
more'truly  realized  the  saying  about  men  laboring  and  others  entering  into  the  fruit  of 
their  labors.  The  illustrations  are  excellent,  and  recourse  has  been  had  to  photographs 
in  rendering  the  more  telling  of  the  physiognomical  expressions.  Even  the  most  an- 
tagonistic of  anti-Darwinians  will  not  hesitate  to  admit  how  much  he  has  learned  from 
A  careful  study  of  the  work  before  us." — Science  Gossip, 


RECENTLY   PUBLISHED. 


A  NEW  EDITION  OF 


Darwin's  Origin  of  Species. 

FROM  THE  SIXTH  AND  LAST  ENGLISH  EDITION, 
Containing  the  Author^ s  Latest  Corrections  and  Additions. 

From  an  entirely  new  set  of  stereotype  plates.     i2mo.     Cloth.     Price,  $2.00. 

D.  APPLETON  &  CO.,  Publishers. 


THE  DESCENT  OF  MAN, 


AND 


SELECTION   IN  RELATION  TO  SEX, 

BY 

CHAS.  DARWIN,  M.  A.,  F.  R.  S. 

Two  Vols.,  12mo. 

Price, $4.00 


In  these  volumes  Mr.  Darwin  has  brought  forward  all  the  facts  and 
arguments  which  science  has  to  offer  in  favor  of  the  doctrine  that  man 
has  arisen  by  gradual  development  from  the  lowest  point  of  animal  life. 
He  had  originally  intended  this  work  as  a  posthumous  publication,  but 
the  extensive  acceptance  of  the  views  unfolded  in  his  book  on  the  "  Origin 
of  Species  "  induced  him  to  believe  that  the  public  were  ripe  for  the  most 
advanced  deductions  from  his  theory  of  "Natural  Selection."  Aside  from 
the  logical  purpose  which  Mr.  Darwin  had  in  view,  his  work  is  an  original 
and  fascinating  contribution  to  the  most  interesting  portion  of  natural 

history.  

From  the  London  Spectator. 
"  For  our  part,  we  find  Dr.  Darwiu's  vindication  of  the  origm  of  man  a  far  more 
woi.derful  vindication  of  Theism  than  Paley'B  'Natural  Theology,'  though  we  do 
not  know,  bo  reticent  is  his  style,  whether  or  not  he  conceives  it  himself" 

From  the  Citizen  and  Bound  Table. 

"  Even  the  charge  of  atheism,  which  was  so  violently  urged  against  Mr.  Dar- 
win, is  now  rarely  heard,  and  theologians,  whose  orthodoxy  is  unquestioned,  have 
ventured  to  admit  that  it  is  possible  to  believe  both  in  Christianity  and  the  Dar- 
winian theory  at  the  same  time." 

From  the  Charleston  Courier. 

"No  one  can  rise  from  an  ordinarily  attentive  consideration  of  Mr.  Darwin'a 
treatise,  without  being  impressed,  not  only  with  the  extent  and  depth  of  the 
knowledge  which  he  has  attained  upon  the  subject  under  treatment,  and  his  long, 
unwearied  lal)or  in  collecting  facts,  but  also  with  his  possession  of  qualities 
equally  rare — the  true  scientific  temper,  the  transparent  candor,  and  the  truth- 
eeoking  soberness,  with  which  he  expresses  to  you  his  conclusions,  and  the  pro- 
cesses by  which  he  reaches  them. 

"  Whether  you  like  his  discourse  or  not — though  you  may  refutse  to  acquiesce 
In  his  conclusions — still  you  are  compelled  to  bear  your  witness,  that  this  mau 
^as  not  been  laboring  to  find  facts  to  support  a  preconceived  theory,  but  that  the 
'Jieory  is  tlie  irrepressible  outgrowth  of  his  accumulated  fads." 
From  the  Evening  Bulletin. 

"  This  theoiy  is  now  indorsed  by  many  eminent  scientists,  who  at  first  com- 
bated it,  including  Sir  Charles  Lyell,  probably  the  most  learned  of  living  geolo- 
ji-ist^",  and  even  by  a  class  of  Cliristian  divines  like  Dr.  McCosh,  who  think  that 
certain  theories  of  cosmogony,  like  the  nebular  hyjjothesis  and  the  law  of  evola- 
tion,  may  be  accepted  without  doing  violence  to  faith." 

Seatfree,  by  mail,  to  any  address  in  the  TJ.  S.,  on  receipt  of  the  price. 

D.  APPLETON  &  CO..  Publishers. 


opinions  of  the  Press  on  the  ^^International  Scientific  Series.'* 


Tyndall's  Forms  of  Water. 

I  vol.,  i2mo.     Cloth.     Illustrated Price,  $1.50. 

"  In  the  volume  now  published,  Professor  Tyndall  has  presented  a  noble  illustration 
of  the  acuteness  and  subtlety  of  his  intellectual  powers,  the  scope  and  insight  of  his 
scientific  vision,  his  singular  command  of  the  appropriate  language  of  exposition,  and 
the  peculiar  vivacity  and  grace  with  which  he  unfolds  the  results  of  intricate  scientific 
research." — N.  V.  Tribune. 

"  The  '  Forms  of  Water,'  by  Professor  Tyndall,  is  an  interesting  and  instructive 
little  volume,  admirably  printed  and  illustrated.  Prepared  expressly  for  this  series,  it 
is  in  some  measure  a  guarantee  of  the  excellence  of  the  volumes  that  will  follow,  and  an 
indication  that  the  publishers  will  spare  no  pains  to  include  in  the  series  the  freshest  in- 
vestigations of  the  best  scientific  minds." — Bostoti  Jouryial. 

"  This  series  is  admirably  commenced  by  this  little  volume  from  the  pen  of  Prof. 
Tyndall.  A  perfect  master  of  his  subject,  he  presents  in  a  style  easy  and  attractive  his 
methods  of  investigation,  and  the  results  obtained,  and  gives  to  the  reader  a  clear  con- 
ception of  all  the  wondrous  transformations  to  which  water  is  subjected." — Churchman. 


II. 

Bagehot's  Physics  and  Politics. 

I  vol.,  l2mo.     Price,  $1.50. 

"  If  the  '  International  Scientific  Series  '  proceeds  as  it  has  begun,  it  will  more  than 
(Ulfil  the  promise  given  to  the  reading  public  in  its  prospectus.  The  first  volume,  by 
Professor  Tyndall,  was  a  model  of  lucid  and  attractive  scientific  exposition  ;  and  now 
we  have  a  second,  by  Mr.  Walter  Bagehot,  v?hich  is  not  only  very  lucid  and  charming^ 
but  also  original  and  suggestive  in  the  highest  degree.  Nowhere  since  the  publicaticrti 
of  Sir  Henry  Maine's  'Ancient  Law,'  have  we  seen  so  many  fruitful  thoughts  sug- 
gested in  the  course  of  a  couple  of  hundred  pages.  .  .  .  To  do  justice  to  Mr.  Bage- 
hot's fertile  book,  would  require  a  long  article.  With  the  best  of  intentions,  we  are 
conscious  of  having  given  but  a  sorry  account  of  it  in  these  brief  paragraphs.  But  wo 
hope  we  have  said  enough  to  commend  it  to  the  attention  of  the  thoughtful  reader." — 
Prof  John  Fiske,  in  the  A  tlaiitic  Monthly. 

"Mr.  Bagehot's  style  is  clear  and  vigorous.  We  refrain  from  giving  a  fuller  ac- 
count of  these  suggestive  essays,  only  because  we  are  sure  that  our  readers  will  find  it 
worth  their  while  to  peruse  the  book  for  themselves ;  and  we  sincerely  hope  that  the 
forthcoming  parts  of  the  'International  Scientific  Series'  will  be  as  interesting."— 
A  thetiteitvi. 

"  Mr.  Bagehot  discusses  an  immense  variety  of  topics  connected  with  the  progress 
of  societies  and  nations,  and  the  development  of  their  distinctive  pecuharities;  and  hit 
book  shows  an  abundance  of  ingenious  and  original  thought." — Alfred  Russeli 
Wallace,  in  Nature. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y. 


opinions  of  the  Press  on  the  '■'•  International  Scientijic  Series.'''' 


III. 


Foods. 


By   Dr.  EDWARD   SMITH. 
I  vol.,  i2mo.     Cloth.     Illustrated Price,  $1.75. 

In  making  up  The  International  Scientific  Series,  Dr.  Edward  Smith  was  se- 
lected as  the  ablest  man  in  England  to  treat  the  important  subject  of  Foods.  His  services 
were  secured  for  the  undertaking,  and  the  little  treatise  he  has  produced  shows  that  the 
choice  of  a  writer  on  this  subject  was  most  fortunate,  as  the  book  is  unquestionably  the 
clearest  and  best-digested  compend  of  the  Science  of  Foods  that  has  appeared  in  our 
language. 

"  The  book  contains  a  series  of  diagrams,  dispteying  the  effects  of  sleep  and  meals 
on  pulsation  and  respiration,  and  of  various  kinds  of  food  on  respiration,  which,  as  the 
results  of  Dr.  Smith's  own  experiments,  possess  a  very  high  value.  We  have  not  far 
to  go  in  this  work  for  occasions  of  favorable  criticism ;  they  occur  throughout,  but  are 
perhaps  most  apparent  in  those  parts  of  the  subject  with  which  Dr.  Smith's  name  is  es- 
pecially linked." — London  Examiner. 

"The  union  of  scientific  and  popular  treatment  in  the  composition  of  this  work  will 
afford  an  attraction  to'  many  readers  who  would  have  been  indifferent  to  purely  theoreti- 
cal details.  .  .  .  Still  his  work  abounds  in  information,  much  of  which  is  of  great  value, 
and  a  part  of  which  could  not  easily  be  obtained  from  other  sources.  Its  interest  is  de- 
cidedly  enhanced  for  students  who  demand  both  clearness  and  exactness  of  statement, 
by  the  profusion  of  well-executed  woodcuts,  diagrams,  and  tables,  which  accompany  th^ 
volume.  .  .  .  The  suggestions  of  the  author  on  the  use  of  tea  and  coffee,  and  of  the  va- 
rious forms  of  alcohol,  although  perhaps  not  strictly  of  a  novel  character,  are  highly  in- 
structive, and  form  an  interesting  portion  of  the  volume." — N.  Y.  Trzbune. 


IV. 

Body  and  Mind. 

THE    THEORIES    OF   THEIR    RELATION. 

By   ALEXANDER    BAIN,    LL.  D. 

I  vol.,   i2mo.      Cloth Price,   $1.50. 

Professor  Bain  is  the  author  of  two  well-known  standard  works  upon  the  Science 
»f  Mind — "The  Senses  and  the  Intellect,"  and  "The  Emotions  and  the  Will."  He  is 
one  of  the  highest  living  authorities  in  the  school  which  holds  that  there  can  be  no  sound 
or  valid  psychology  unless  the  mind  and  the  body  are  studied,  as  they  exist,  together. 

"  It  contains  a  forcible  statement  of  the  connection  between  mind  and  body,  study- 
ing their  subtile  interworkings  by  the  light  of  the  most  recent  physiologic.il  investiga- 
tions. The  summaiy  in  Chapter  V.,  of  the  investigations  of  Dr.  Lionel  Beale  of  the 
embodiment  of  the  intellectual  functions  in  the  cerebral  system,  will  be  found  the 
freshest  and  most  interesting  part  of  his  book.  Prof  Bain's  own  theory  of  the  connec- 
tion between  the  mental  and  the  bodily  part  in  man  is  stated  by  himself  to  be  as  follows : 
There  is  '  one  substance,  with  two  sets  of  properties,  two  sides,  the  physical  and  the 
mental — a  double-faced  unity.'  While,  in  the  strongest  manner,  asserting  the  union 
of  mind  with  brain,  he  yet  denies  'the  association  of  union  in  place,'  but  asserts  the 
union  of  close  succession  in  time,'  holding  that  '  the  same  being  is,  by  alternate  fits,  un- 
der extended  and  under  unextended  consciousness."  ' — Cliristiaii  Register. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y. 


opinions  of  the  Press  on  the  "  International  Scicittijic  Series." 


The  Study  of  Sociology. 

By   HERBERT   SPENCER. 

I  vol.,  i2mo.     Cloth Price,  $1.50. 

"The  philosopher  whose  distinguished  name  gives  weight  and  influence  to  this  vol- 
ume, has  given  in  its  pages  some  of  the  finest  specimens  of  reasoning  in  all  its  forms 
and  departments.  There  is  a  fascination  in  his  array  of  facts,  incidents,  and  opinions, 
which  draws  on  the  reader  to  ascertain  his  conclusions.  The  coolness  and  calmness  of 
his  treatment  of  acknowledged  difficulties  and  grave  objections  to  his  theories  win  for 
him  a  close  attention  and  sustained  effort,  on  the  part  of  the  reader,  to  comprehend,  fol- 
low, grasp,  and  appropriate  his  principles.  This  book,  independently  of  its  bearing 
upon  sociology,  is  valuable  as  lucidly  showing  what  those  essential  characteristics  are 
which  entitle  any  arrangement  and  connection  of  facts  and  deductions  to  be  called  a 
science." — Episcopalian. 

"  This  work  compels  admiration  by  the  evidence  which  it  gives  of  immense  re- 
search, study,  and  observation,  and  is,  withal,  written  in  a  popular  and  very  pleasing 
style.     It  is  a  fascinating  work,  as  well  as  one  of  deep  practical  thought." — Bost.  Post. 

"  Herbert  Spencer  is  unquestionably  the  foremost  living  thinker  in  the  psychological 
and  sociological  fields,  and  this  volume  is  an  important  contribution  to  the  science  of 
which  it  treats.  ...  It  will  prove  more  popular  than  any  of  its  author's  other  creations, 
for  it  is  more  plainly  addressed  to  the  people  and  has  a  more  practical  and  less  specu- 
lative cast.  It  will  require  thought,  but  it  is  well  worth  thinking  about." — Albany 
Evetiing  Journal. 

VI. 

The   New  Chemistry. 

By  JOSIAH  P.  COOKE,  Jr., 

Erving  Professor  of  Chemistry  and  Mineralogy  in  Harvard  University. 
I  vol.,   l2mo.     Cloth Price,  $2.00. 

"The  book  of  Prof  Cooke  is  a  model  of  the  modem  popular  science  work.  It  has 
just  the  due  proportion  of  fact,  philosophy,  and  true  romance,  to  make  it  a  fascinating 
companion,  either  for  the  voyage  or  the  study." — Daily  Graphic. 

"  This  admirable  monograph,  by  the  distinguished  Erving  Professor  of  Chemistry 
in  Harvard  University,  is  the  first  American  contribution  to  'The  International  Scien- 
tific Series,'  and  a  more  attractive  piece  of  work  in  the  way  of  popular  exposition  upon 
a  difficult  subject  h.is  not  appeared  in  a  long  time.  It  not  only  well  sustains  the  char- 
acter of  the  volumes  with  which  it  is  associated,  but  its  reproduction  in  European  coun- 
tries will  be  an  honor  to  American  science." — iVcto  York  Triii/ne. 

"  AH  the  chemists  in  the  country  will  enjoy  its  perusal,  and  many  will  seize  upon  it 
as  a  thing  longed  for.  For,  to  those  advanced  students  who  have  kept  well  abreast  ol 
the  chemical  tide,  it  offers  a  calm  philosophy.  To  those  others,  youngest  of  the  class, 
who  have  emerged  from  the  schools  since  new  methods  have  prevailed,  it  presents  a 
generalization,  drawing  to  its  use  all  the  data,  the  relations  of  which  the  newly-fledged 
fact-seeker  may  but  dimly  perceive  without  its  aid.  .  .  .  To  the  old  chemists,  Prof. 
Cooke's  treatise  is  like  a  message  from  beyond  the  mountain.  They  have  heard  0/ 
changes  in  the  science;  the  clash  of  the  battle  of  old  and  new  theories  has  stirred  them 
from  afer.  The  tidings,  too,  had  come  that  the  old  had  given  way ;  and  little  more  than 
this  they  knew.  .  .  .  Prof  Cooke's  '  New  Chemistry '  must  do  wide  service  in  bringing 
to  close  sight  the  little  known  and  the  longed  for.  .  .  .  As  a  philosophy  it  is  elemen' 
tary,  but,  as  a  book  of  science,  ordinary  readers  will  find  it  sufficiently  advanced."-' 
Uiica  Morning  Herald. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y, 


opinions  of  the  Press  on  the  '"'' International  Scientific  Series" 

VII. 

The  Conservation  of  Energy. 

By  BALFOUR  STEWART,  LL.  D.,  F.  R.  S. 

With  an  Appendix  treating  of  the  Vital  and  Mental  Applications  of  the  Doctrine. 
I  vol.,  i2mo.     Cloth.     Price,  $1.50. 

"  The  author  has  succeeded  in  presenting  the  facts  in  a  clear  and  satisfactory  manner, 
using  simple  language  and  copious  illustration  in  the  presentation  of  facts  and  prin- 
ciples, confining  himself,  however,  to  the  physical  aspect  of  the  subject.  In  the  Ap- 
pendix the  operation  of  the  principles  in  the  spheres  of  life  and  mind  is  supplied  by 
the  essays  of  Professors  Le  Oonte  and  Bain." — Ohio  Farmer. 

"  Prof.  Stewart  is  one  of  the  best  known  teachers  in  Owens  College  in  Manchester. 

"The  volume  of  The  Intehnational  Scientific  Series  now  before  us  is  an  ex- 
cellent illustration  of  the  true  method  of  teaching,  and  will  well  compare  with  Prof. 
Tyndali's  charming  little  book  in  the  same  series  on  '  Forms  of  Water,"  with  illustra- 
tions enough  to  make  clear,  but  not  to  conceal  his  thoughts,  in  a  style  simple  and 
brief." — Chriitian  Register,  Boston. 

"  The  writer  has  wonderful  ability  to  compress  much  information  into  a  few  words. 
It  is  a  rich  treat  to  read  such  a  book  as  this,  when  there  is  so  much  beauty  and  force 
combined  with  such  simplicity. — Eastern  Press. 


VIII. 

Animal  Locomotion; 

Or,  WALKING,   SWIMMING,  AND   FLYING. 

With  a  Dissertation  on  Aeronautics. 

By  J.  BELL  PETTIGREW,  M.  D.,  F.  R.  S.,  F.  R.  S.  E., 
F.  R.C.  P.E. 

I  vol.,  i2mo Price,  $1.75. 

"  This  work  is  more  than  a  contribution  to  the  stock  of  entertaining  knowledge, 
though,  if  it  only  pleased,  that  would  be  sufficient  excuse  for  its  publication.  But  Dr. 
Pettigrew  has  given  his  time  to  these  investigations  with  the  ultimate  purpose  of  solv- 
ing the  difficult  problem  of  Aeronautics.  To  this  he  devotes  the  last  fifty  pages  of  his 
book.  Dr.  Pettigrew  is  confident  that  man  will  yet  conquer  the  domain  of  the  air."—' 
N.   Y.  Jojirnal  of  Commerce. 

"Most  persons  claim  to  know  how  to  walk,  but  few  could  explain  the  mechanical 
principles  involved  in  this  most  ordinary  transaction,  and  will  be  surprised  that  the 
movements  of  bipeds  and  quadrupeds,  the  darting  and  rushing  motion  of  fish,  and  the 
erratic  flight  of  the  denizens  of  the  air,  are  not  only  anologous,  but  can  be  reduced  to 
similar  formula.  The  work  is  profusely  illustrated,  and,  without  reference  to  the  theory 
it  is  designed  to  expound,  will  be  regarded  as  a  valuable  addition  to  natural  history." 
— Omaha  Republic. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y, 


opinions  of  the  Press  on  the  ^^International  Scientific  Series." 


IX. 

Responsibility  in  Mental  Disease. 

By  HENRY   MAUDSLEY,    M.  D,, 

Fellow  of  the  Royal  College  of  Physicians ;  Professor  of  Medical  Jurisprudence 
in  University  College,  London. 

I  vol.,   i2nio.     Cloth.     .     .     Price,  $1.50. 

"  Having  lectured  in  a  medical  college  on  Mental  Disease,  this  book  has  been  a 
feast  to  us.  It  handles  a  great  subject  in  a  masterly  manner,  and,  in  our  judgment,  the 
positions  taken  by  the  author  are  correct  and  well  sustained." — Pastor  and  People. 

"  The  author  is  at  home  in  his  subject,  and  presents  his  views  in  an  almost  singu- 
larly clear  and  satisfactory  manner.  .  .  .  The  volume  is  a  valuable  contribution  to  one 
of  the  most  difficult,  and  at  the  same  time  one  of  the  most  important  subjects  of  inves- 
tigation at  the  present  day." — N.  V,  Observer. 

"  It  is  a  work  profound  and  searching,  and  abounds  in  wisdom." — Pittsburg  Com- 
mercial. 

"  Handles  the  important  topic  with  masterly  power,  and  its  suggestions  are  prac- 
tical and  of  great  value." — Providence  Press. 


The  Science  of  Law. 

By  SHELDON  AMOS,  M.  A., 

Professor  of  Jurisprudence  in  University  College,  London;  author  of  "A  Systematic 

View  of  the  Science  of  Jurisprudence,"  "  An  English  Code,  its  Difficulties 

and  the  Modes  of  overcoming  them,"  etc.,  etc. 

I  vol.,   i2mo.     Cloth Price,  $1.75. 

"The  valuable  series  of  '  International  Scientific'  works,  prepared  by  eminent  spe- 
cialists, with  the  intention  of  popularizing  information  in  their  several  branches  of 
knowledge,  has  received  a  good  accession  in  this  compact  and  thoughtful  volume.  It 
is  a  difficult  task  to  give  the  outlines  of  a  complete  theory  of  law  in  a  portable  volume, 
which  he  who  runs  may  read,  and  probably  Professor  Amos  himself  would  be  the  last 
to  claim  that  he  has  perfectly  succeeded  in  doing  this.  But  he  has  certainly  done  much 
to  clear  the  science  of  law  from  the  technical  obscurities  which  darken  it  to  minds  which 
have  had  no  legal  training,  and  to  make  clear  to  his  '  lay '  readers  in  how  true  and  high  a 
sense  it  can  assert  its  right  to  be  considered  a  science,  and  not  a  mere  practice." — The 
Christian  Register. 

"The  works  of  Bentham  and  Austin  are  abstruse  and  philosophical,  and  Maine's 
require  hard  study  and  a  certain  amount  of  special  training.  The  writers  also  pursue 
different  lines  of  investigation,  and  can  only  be  regarded  as  comprehensive  in  the  de- 
partments they  confined  themselves  to.  It  was  left  to  Amos  to  gather  up  the  result 
and  present  the  science  in  its  fullness.  The  unquestionable  merits  of  this,  his  last  book, 
are,  that  it  contains  a  complete  treatment  of  a  subject  which  has  hitherto  been  handled 
by  specialists,  and  it  opens  up  that  subject  to  every  inquiring  mind.  .  .  .  To  do  justice 
to  '  The  Science  of  Law '  would  require  a  longer  review  than  we  have  space  for.  We 
have  read  no  more  interesting  and  instructive  book  for  some  time.  Its  themes  concern 
every  one  who  renders  obedience  to  laws,  and  who  would  have  those  laws  the  best 
possible.  The  tide  of  legal  reform  which  set  in  fifty  years  ago  has  to  sweep  yethighei 
if  the  flaws  in  our  jurisprudence  are  to  be  removed.  The  process  of  change  cannot  be 
better  guided  than  by  a  well-informed  public  mind,  and  Prof.  Amos  has  done  great 
service  in  materially  helping  to  promote  this  end." — 'Buffalo  Courier. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y- 


opinions  of  the  Press  on  the  ^^International  Scientific  Series." 

XI. 

Animal   Mechanism, 

A  Treatise  on  Terrestrial  and  Aerial  Locomotion. 

By  E.  J.  MAREY, 

Professor  at  the  College  of  France,  and   Member  of  the  Academy  of  Medicine. 

With  117  Illustrations,  drawn  and  engraved  under  the  direction  of  the  author. 

I  vol.,  i2mo.     Cloth Price,  $1.75 

"  We  hope  that,  in  the  short  glance  which  we  have  taken  of  some  of  the  most  im- 
portant points  discussed  in  the  work  before  us,  we  have  succeeded  in  interesiing  our 
readers  sufficiently  in  its  contents  to  make  them  curious  to  learn  more  of  its  subject- 
matter.     We  cordially  recommend  it  to  their  attention. 

"  The  author  of  the  present  work,  it  is  well  known,  stands  at  the  head  of  those 
physiologists  who  have  investigated  the  mechanism  of  animal  dynamics — indeed,  we 
may  almost  say  that  he  has  made  the  subject  his  own.  By  the  originality  of  his  con- 
ceptions, the  ingenuity  of  his  constructions,  the  skill  of  his  analysis,  and  the  persever- 
ance of  his  investigations,  he  has  surpassed  all  others  in  the  power  of  unveiling  the 
complex  and  intricate  movements  of  animated  beings." — Popular  Science  Monthly. 


XII. 

History   of  the    Conflict    between 
Rehgion  and  Science. 

By  JOHN  WILLIAM  DRAPER,  M.  D.,  LL.  D., 

Author  of  "  The  Intellectual  Development  of  Europe." 

I  vol.,  i2mo. Price,  $1.75. 

"This  little  '  History'  would  have  been  a  valuable  contribution  to  literature  at  any 
lime,  and  is,  in  fact,  an  admirable  text-book  upon  a  subject  that  is  at  present  engross- 
ing the  attention  of  a  large  number  of  the  most  serious-minded  people,  and  it  is  no 
small  compliment  to  the  sagacity  of  its  distinguished  author  that  he  has  so  well  gauged 
the  requirements  of  the  times,  and  so  adequately  met  them  by  the  preparation  of  this 
volume.  It  remains  to  be  added  that,  while  the  writer  has  flinched  from  no  responsi- 
bility in  his  statements,  and  has  written  with  entire  fidelity  to  the  demands  of  truth 
and  justice,  there  is  not  a  word  in  his  book  that  can  give  offense  to  candid  and  fair- 
minded  readers." — A^.  Y.  Eiiening  Post. 

"  The  key-note  to  this  volume  is  found  in  the  antagonism  between  the  progressive 
tendencies  of  the  human  mind  and  the  pretensions  of  ecclesiastical  authority,  as  devel- 
oped in  the  history  of  modern  science.  No  previous  writer  has  treated  the  subject 
from  this  point  of  view,  and  the  present  monograph  will  be  found  to  possess  no  less 
originality  of  conception  than  vigor  of  reasoning  and  wealth  of  erudition.  .  .  .  The 
method  of  Dr.  Draper,  in  his  treatment  of  the  various  questions  that  come  up  for  dis- 
cussion, is  marked  by  singular  impartiality  as  well  as  consummate  ability.  Through- 
out his  work  he  maintains  the  position  of  an  historian,  not  of  an  advocate.  His  tone  is 
tranquil  and  serene,  as  becomes  the  search  after  truth,  with  no  trace  of  the  impassioned 
ardor  of  controversy.  He  endeavors  so  far  to  identify  himself  with  the  contending 
parties  as  to  gain  a  clear  comprehension  of  their  motives,  but,  at  the  same  time,  he 
iubmits  their  actions  to  the  tests  of  a  cool  and  impartial  examination." — N.  Y.  Tribune. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y. 


opinions  of  the  Press  on  the  " International  Scientific  Series" 

XIII. 

THE    DOCTRINE   OF 

Descent,    and    Darwinism. 

By  OSCAR  SCHMIDT, 
Professor  in  the  University  of  Strasburg. 

With  26  Woodcuts. 
I  vol.,  i2ino.     Cloth Price,  $1.50. 

"  The  entire  subject  is  discussed  with  a  freshness,  as  well  as  an  elaboration  of  de- 
tail, that  renders  his  work  interesting  in  a  more  than  usual  degree.  The  facts  upon 
which  the  Darwinian  theory  is  based  are  presented  in  an  effective  manner,  conclusions 
are  ably  defended,  and  the  question  is  treated  in  more  compact  and  available  style 
than  in  any  other  work  on  the  same  topic  that  has  yet  appeared.  Itris  a  valuable  ad- 
dition to  the  '  International  Scientific  Series.'  " — Boston  Post. 

"The  present  volume  is  the  thirteenth  of  the  'International  Scientific  Series,'  and 
is  one  of  the  most  interesting  of  all  of  them.  The  subject-matter  is  handled  with  a 
great  deal  of  skill  and  earnestness,  and  the  courage  of  the  author  in  avowing  his  opin- 
ions is  much  to  his  credit.  .  .  .  This  volume  certainly  merits  a  careful  perusal." — 
Hartford  Evening  Post. 

"  The  volume  which  Prof  Schmidt  has  devoted  to  this  theme  is  a  valuable  contri- 
bution to  the  Darwinian  literature.  Philosophical  in  method,  and  eminently  candid, 
it  shows  not  only  the  ground  which  Darwin  had  in  his  researches  made,  and  conclu- 
sions reached  before  him  to  plant  his  theory  upon,  but  shows,  also,  what  that  theory 
really  is,  a  point  upon  which  many  good  people  who  talk  very  earnestly  about  the 
matter  are  very  imperfectly  informed." — Detroit  Free  Press. 


XIV. 

The  Chemistry  of  Light  and 
Photography ; 

In  its  Application  to  Art,  Science,  and  Industry. 

By  Dr.  HERMANN  VOGEL, 
Professor  in  the  Royal  Industrial  Academy  of  Berlin. 

With  100  Illustrations. 
l2mo Price,  $2.00. 

"Out  of  Photography  has  sprung  a  new  science — the  Chemistry  of  Light — and,  in 
giving  a  popular  view  to  the  one,  Dr.  Vogel  has  presented  an  analysis  of  the  principles 
and  processes  of  the  other.  His  treatise  is  as  entertaining  as  it  is  instructive,  pleas- 
antly combining  a  history  of  the  progress  and  practice  of  photography — from  the  first 
rough  experiments  of  Wedgwood  and  Davy  with  sensitized  paper,  in  1802,  down  to 
the  latest  improvements  of  the  art — with  technical  illustrations  of  the  >cientific  theories 
on  which  the  art  is  based.  It  is  the  first  attempt  in  any  manual  of  photography  to  set 
forth  adequately  the  just  claims  of  the  invention,  both  from  an  artistic  and  a  scientific 
point  of  view,  and  it  must  be  conceded  that  the  effort  has  been  ably  conducted."— 
Chicago  Tribune. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y. 


Opiniotls  of  the  Press  on  the  '■'' International  Scientific  Series.^* 


Fungi ; 

THEIR   NATURE,  INFLUENCE,  AND    USES. 

By  M.  C.   COOKE,  M.  A.,  LL.  D. 

Edited  by  Rev.  M.  J.  BERKELEY,  M.  A.,  F.  L.  S. 

With  109  Illustrations.     Price,  $1.50. 

"Even  if  the  name  of  the  author  of  this  work  were  not  deservedly  eminent,  that  of 
the  editor,  who  has  long  stood  at  the  head  of  the  British  fungologists,  would  be  a  suf- 
ficient voucher  for  the  accuracy  of  one  of  the  best  botanical  monographs  ever  issued 
from  the  press.  .  .  .  The  structure,  germination,  and  growth  of  all  these  widely-dif- 
fused organisms,  their  habitats  and  influences  for  good  and  evil,  are  systematically 
described." — Ne^v  York  World. 

"Dr.  Cooke's  book  contains  an  admirable  re'snindoi  what  is  known  on  the  struct- 
ure, growth,  and  reproduction  of  fungi,  together  with  ample  bibliographical  references 
to  original  sources  of  information." — Louion  Atheticsiim. 

"  The  production  of  a  work  like  the  one  now  under  review  represents  a  large 
amount  of  laborious,  difficult,  and  critical  work,  and  one  in  which  a  serious  slip  or  fatal 
error  would  be  one  of  the  easiest  matters  possible,  but,  as  far  as  we  are  able  to  judge, 
the  new  hand-book  seems  in  every  way  well  suited  to  the  requirements  of  all  beginners 
in  the  difficult  and  involved  study  of  fungology." — The  Gardener's  Chronicle  {Lon- 
don). 

XVI. 

The  Life  and  Growth  of  Language: 

AN    OUTLIKE     OF    LINGUISTIC    SCIENCE. 

By   WILLIAM  DIVIGHT  WHITNEY, 

Professor  of  Sanskrit  and  Comparative  Philology  in  Yale  College. 

I  vol.,  i2mo.     Cloth.     Price,  $1.50. 

"Prof  Whitney  is  to  be  commended  for  giving  to  the  public  the  results  of  his  ripe 
scholarship  and  unusually  profound  researches  in  simple  language.  He  draws  illus- 
trations and  examples  of  the  principles  which  he  wishes  to  impact,  from  common  hfe 
and  the  words  in  frequent  use. 

"  The  topics  discussed  in  this  volume  are,  for  the  most  part,  those  which  have 
been  already  treated  by  other  writers  on  philology,  and  even  by  the  author  himself,  in 
his  volume  on  'Language,  and  the  Study  of  Language,'  published  a  few  years  ago, 
and,  though  many  of  the  truths  here  set  forth  are  those  with  which  students  in  the 
same  line  of  investigation  are  generally  familiar,  all  will  rejoice  to  see  them  restated  in 
such  a  fresh  and  simple  way. 

"This  work,  while  valuable  to  scholars,  will  be  interesting  to  every  one." — The 
Churchman. 

"  This  work  is  an  important  contribution  to  a  science  which  has  advanced  steadily 
under  conditions  that  appear  constantly  to  throw  an  increasing  light  on  difficult  ques- 
tions, and  at  each  step  clear  the  way  for  further  discoveries." — Chicago  Inter-Occaii. 

"Prof  Whitney  is  undoubtedly  one  of  the  foremost  of  English-speaking  philologists, 
and  occupies  an  enviable  position  in  the  wider  circle  of  European  students  of  language. 

"His  style,  clear,  simple,  picturesque,  abounding  in  striking  illustrations,  and  apt 
in  compari.nons,  is  admirably  fitted  to  be  the  vehicle  of  a  popular  treatise  like  the  work 
under  consideration." — Port  land  Daily  Press. 

D.  APPLETON  &  CO.,  Publishers,  549  &  551  Broadway,  N.  Y. 


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